diff --git a/FU/Benchmarks.pod b/FU/Benchmarks.pod
index 135a582..55f00db 100644
--- a/FU/Benchmarks.pod
+++ b/FU/Benchmarks.pod
@@ -55,7 +55,7 @@ API object from L<JSON::XS> documentation.
   Cpanel::JSON::XS    112845/s    102903/s    101843/s
         JSON::SIMD    125127/s    116569/s    117446/s
           JSON::XS    128792/s    118616/s    117257/s
-          FU::Util    126324/s    106597/s     62633/s
+          FU::Util    136151/s    115564/s    120184/s
 
 Object (small)
 
@@ -64,7 +64,7 @@ Object (small)
   Cpanel::JSON::XS     42755/s     27849/s     18920/s
         JSON::SIMD     48487/s     30266/s     22527/s
           JSON::XS     48980/s     30558/s     24065/s
-          FU::Util     43172/s     24882/s      6818/s
+          FU::Util     49346/s     26316/s     20768/s
 
 Object (large)
 
@@ -73,7 +73,7 @@ Object (large)
   Cpanel::JSON::XS     29889/s     11629/s     16264/s
         JSON::SIMD     33950/s     12050/s     22649/s
           JSON::XS     34534/s     12399/s     23418/s
-          FU::Util     37298/s     12001/s      5413/s
+          FU::Util     40482/s     13735/s     18161/s
 
 Object (large, mixed unicode)
 
@@ -82,7 +82,7 @@ Object (large, mixed unicode)
   Cpanel::JSON::XS     20563/s      1402/s      7590/s
         JSON::SIMD     24996/s      1401/s     15959/s
           JSON::XS     26915/s      1454/s      8848/s
-          FU::Util     24280/s     10461/s      5998/s
+          FU::Util     24706/s     11403/s      9379/s
 
 Small integers
 
@@ -91,7 +91,7 @@ Small integers
   Cpanel::JSON::XS      7235/s      6008/s
         JSON::SIMD      8058/s      4335/s
           JSON::XS      8036/s      5998/s
-          FU::Util      8344/s      5656/s
+          FU::Util      8701/s      5902/s
 
 Large integers
 
@@ -100,7 +100,7 @@ Large integers
   Cpanel::JSON::XS     31337/s     48514/s
         JSON::SIMD     36876/s     52446/s
           JSON::XS     36665/s     48689/s
-          FU::Util    115559/s     62931/s
+          FU::Util    122700/s     62048/s
 
 ASCII strings
 
@@ -109,7 +109,7 @@ ASCII strings
   Cpanel::JSON::XS    117604/s     43652/s
         JSON::SIMD    136214/s     50865/s
           JSON::XS    136486/s     40599/s
-          FU::Util    168713/s     32742/s
+          FU::Util    192974/s     43327/s
 
 Unicode strings
 
@@ -118,7 +118,7 @@ Unicode strings
   Cpanel::JSON::XS     92871/s     66032/s
         JSON::SIMD    106664/s    100555/s
           JSON::XS    104716/s     60538/s
-          FU::Util    108032/s     36331/s
+          FU::Util    124756/s     49825/s
 
 String escaping (few)
 
@@ -127,7 +127,7 @@ String escaping (few)
   Cpanel::JSON::XS    133222/s    104174/s
         JSON::SIMD    155205/s    148939/s
           JSON::XS    123154/s     92594/s
-          FU::Util    206172/s     76491/s
+          FU::Util    202792/s     85352/s
 
 String escaping (many)
 
@@ -136,7 +136,7 @@ String escaping (many)
   Cpanel::JSON::XS    139049/s     99260/s
         JSON::SIMD    152317/s    113037/s
           JSON::XS    153421/s    107918/s
-          FU::Util    132774/s     64880/s
+          FU::Util    132523/s     78199/s
 
 
 
@@ -144,122 +144,122 @@ String escaping (many)
 
 # Cached data used by bench.PL. Same as the formatted tables above but easier to parse.
 json/api	Canonical	Cpanel::JSON::XS	102903
-json/api	Canonical	FU::Util	106597
+json/api	Canonical	FU::Util	115564
 json/api	Canonical	JSON::PP	4973
 json/api	Canonical	JSON::SIMD	116569
 json/api	Canonical	JSON::XS	118616
 json/api	Decode	Cpanel::JSON::XS	101843
-json/api	Decode	FU::Util	62633
+json/api	Decode	FU::Util	120184
 json/api	Decode	JSON::PP	1290
 json/api	Decode	JSON::SIMD	117446
 json/api	Decode	JSON::XS	117257
 json/api	Encode	Cpanel::JSON::XS	112845
-json/api	Encode	FU::Util	126324
+json/api	Encode	FU::Util	136151
 json/api	Encode	JSON::PP	5397
 json/api	Encode	JSON::SIMD	125127
 json/api	Encode	JSON::XS	128792
 json/intl	Decode	Cpanel::JSON::XS	48514
-json/intl	Decode	FU::Util	62931
+json/intl	Decode	FU::Util	62048
 json/intl	Decode	JSON::PP	330
 json/intl	Decode	JSON::SIMD	52446
 json/intl	Decode	JSON::XS	48689
 json/intl	Encode	Cpanel::JSON::XS	31337
-json/intl	Encode	FU::Util	115559
+json/intl	Encode	FU::Util	122700
 json/intl	Encode	JSON::PP	2174
 json/intl	Encode	JSON::SIMD	36876
 json/intl	Encode	JSON::XS	36665
 json/ints	Decode	Cpanel::JSON::XS	6008
-json/ints	Decode	FU::Util	5656
+json/ints	Decode	FU::Util	5902
 json/ints	Decode	JSON::PP	29
 json/ints	Decode	JSON::SIMD	4335
 json/ints	Decode	JSON::XS	5998
 json/ints	Encode	Cpanel::JSON::XS	7235
-json/ints	Encode	FU::Util	8344
+json/ints	Encode	FU::Util	8701
 json/ints	Encode	JSON::PP	113
 json/ints	Encode	JSON::SIMD	8058
 json/ints	Encode	JSON::XS	8036
 json/objl	Canonical	Cpanel::JSON::XS	11629
-json/objl	Canonical	FU::Util	12001
+json/objl	Canonical	FU::Util	13735
 json/objl	Canonical	JSON::PP	744
 json/objl	Canonical	JSON::SIMD	12050
 json/objl	Canonical	JSON::XS	12399
 json/objl	Decode	Cpanel::JSON::XS	16264
-json/objl	Decode	FU::Util	5413
+json/objl	Decode	FU::Util	18161
 json/objl	Decode	JSON::PP	105
 json/objl	Decode	JSON::SIMD	22649
 json/objl	Decode	JSON::XS	23418
 json/objl	Encode	Cpanel::JSON::XS	29889
-json/objl	Encode	FU::Util	37298
+json/objl	Encode	FU::Util	40482
 json/objl	Encode	JSON::PP	916
 json/objl	Encode	JSON::SIMD	33950
 json/objl	Encode	JSON::XS	34534
 json/objs	Canonical	Cpanel::JSON::XS	27849
-json/objs	Canonical	FU::Util	24882
+json/objs	Canonical	FU::Util	26316
 json/objs	Canonical	JSON::PP	827
 json/objs	Canonical	JSON::SIMD	30266
 json/objs	Canonical	JSON::XS	30558
 json/objs	Decode	Cpanel::JSON::XS	18920
-json/objs	Decode	FU::Util	6818
+json/objs	Decode	FU::Util	20768
 json/objs	Decode	JSON::PP	206
 json/objs	Decode	JSON::SIMD	22527
 json/objs	Decode	JSON::XS	24065
 json/objs	Encode	Cpanel::JSON::XS	42755
-json/objs	Encode	FU::Util	43172
+json/objs	Encode	FU::Util	49346
 json/objs	Encode	JSON::PP	905
 json/objs	Encode	JSON::SIMD	48487
 json/objs	Encode	JSON::XS	48980
 json/obju	Canonical	Cpanel::JSON::XS	1402
-json/obju	Canonical	FU::Util	10461
+json/obju	Canonical	FU::Util	11403
 json/obju	Canonical	JSON::PP	699
 json/obju	Canonical	JSON::SIMD	1401
 json/obju	Canonical	JSON::XS	1454
 json/obju	Decode	Cpanel::JSON::XS	7590
-json/obju	Decode	FU::Util	5998
+json/obju	Decode	FU::Util	9379
 json/obju	Decode	JSON::PP	86
 json/obju	Decode	JSON::SIMD	15959
 json/obju	Decode	JSON::XS	8848
 json/obju	Encode	Cpanel::JSON::XS	20563
-json/obju	Encode	FU::Util	24280
+json/obju	Encode	FU::Util	24706
 json/obju	Encode	JSON::PP	845
 json/obju	Encode	JSON::SIMD	24996
 json/obju	Encode	JSON::XS	26915
 json/strel	Decode	Cpanel::JSON::XS	99260
-json/strel	Decode	FU::Util	64880
+json/strel	Decode	FU::Util	78199
 json/strel	Decode	JSON::PP	360
 json/strel	Decode	JSON::SIMD	113037
 json/strel	Decode	JSON::XS	107918
 json/strel	Encode	Cpanel::JSON::XS	139049
-json/strel	Encode	FU::Util	132774
+json/strel	Encode	FU::Util	132523
 json/strel	Encode	JSON::PP	2230
 json/strel	Encode	JSON::SIMD	152317
 json/strel	Encode	JSON::XS	153421
 json/stres	Decode	Cpanel::JSON::XS	104174
-json/stres	Decode	FU::Util	76491
+json/stres	Decode	FU::Util	85352
 json/stres	Decode	JSON::PP	350
 json/stres	Decode	JSON::SIMD	148939
 json/stres	Decode	JSON::XS	92594
 json/stres	Encode	Cpanel::JSON::XS	133222
-json/stres	Encode	FU::Util	206172
+json/stres	Encode	FU::Util	202792
 json/stres	Encode	JSON::PP	4258
 json/stres	Encode	JSON::SIMD	155205
 json/stres	Encode	JSON::XS	123154
 json/strs	Decode	Cpanel::JSON::XS	43652
-json/strs	Decode	FU::Util	32742
+json/strs	Decode	FU::Util	43327
 json/strs	Decode	JSON::PP	341
 json/strs	Decode	JSON::SIMD	50865
 json/strs	Decode	JSON::XS	40599
 json/strs	Encode	Cpanel::JSON::XS	117604
-json/strs	Encode	FU::Util	168713
+json/strs	Encode	FU::Util	192974
 json/strs	Encode	JSON::PP	2922
 json/strs	Encode	JSON::SIMD	136214
 json/strs	Encode	JSON::XS	136486
 json/stru	Decode	Cpanel::JSON::XS	66032
-json/stru	Decode	FU::Util	36331
+json/stru	Decode	FU::Util	49825
 json/stru	Decode	JSON::PP	254
 json/stru	Decode	JSON::SIMD	100555
 json/stru	Decode	JSON::XS	60538
 json/stru	Encode	Cpanel::JSON::XS	92871
-json/stru	Encode	FU::Util	108032
+json/stru	Encode	FU::Util	124756
 json/stru	Encode	JSON::PP	5144
 json/stru	Encode	JSON::SIMD	106664
 json/stru	Encode	JSON::XS	104716
diff --git a/c/common.c b/c/common.c
index 5b63046..6139e04 100644
--- a/c/common.c
+++ b/c/common.c
@@ -2,29 +2,47 @@
 
 typedef struct {
     SV *sv;
+    SV *mortal;
     char *cur;
     char *end;
     size_t maxlen;
+    int setutf8;
+    char sbuf[4096];
 } fustr;
 
-/* sv must be a new SV with a preallocated buffer */
-static void fustr_init_(pTHX_ fustr *s, SV *sv, size_t maxlen) {
-    s->sv = sv;
-    SvPOK_only(s->sv);
-    s->cur = SvPVX(s->sv);
-    s->end = SvEND(s->sv);
+static void fustr_init_(pTHX_ fustr *s, SV *mortal, size_t maxlen) {
+    s->sv = NULL;
+    s->cur = s->sbuf;
+    s->end = s->sbuf + (maxlen > sizeof s->sbuf ? sizeof s->sbuf : maxlen);
     s->maxlen = maxlen;
+    s->mortal = mortal;
+    s->setutf8 = 0;
 }
 
+#define fustr_start(s) (((s)->sv ? SvPVX((s)->sv) : (s)->sbuf))
+
 static void fustr_grow(pTHX_ fustr *s, size_t add) {
-    size_t off = s->cur - SvPVX(s->sv);
-    size_t newlen = 64;
+    size_t off = s->cur - (s->sv ? SvPVX(s->sv) : s->sbuf);
+    size_t newlen = sizeof s->sbuf;
+    char *buf;
     add += off;
     if (add > s->maxlen) croak("maximum string length exceeded");
     /* Increment to next power of two; SvGROW's default strategy is slow */
     while (newlen < add) newlen <<= 1;
     if (newlen > s->maxlen) newlen = s->maxlen;
-    char *buf = SvGROW(s->sv, newlen);
+    if (s->sv) {
+        buf = SvGROW(s->sv, newlen);
+    } else {
+        if (s->mortal) {
+            s->sv = s->mortal;
+            sv_setpv_bufsize(s->sv, off, newlen);
+        } else {
+            s->sv = newSV(newlen);
+        }
+        SvPOK_only(s->sv);
+        buf = SvPVX(s->sv);
+        memcpy(buf, s->sbuf, off);
+    }
     s->cur = buf + off;
     s->end = buf + (SvLEN(s->sv) > s->maxlen ? s->maxlen : SvLEN(s->sv));
 }
@@ -39,6 +57,11 @@ static inline void fustr_write_(pTHX_ fustr *s, const char *str, size_t n) {
     s->cur += n;
 }
 
+static inline void fustr_write_ch_(pTHX_ fustr *s, char x) {
+    fustr_reserve_(aTHX_ s, 1);
+    *(s->cur++) = x;
+}
+
 /* Adds n uninitialized bytes to the string and returns a buffer to write the data to */
 static inline char *fustr_write_buf_(pTHX_ fustr *s, size_t n) {
     fustr_reserve_(aTHX_ s, n);
@@ -50,13 +73,19 @@ static inline char *fustr_write_buf_(pTHX_ fustr *s, size_t n) {
 static SV *fustr_done_(pTHX_ fustr *s) {
     fustr_reserve_(aTHX_ s, 1);
     *s->cur = 0;
-    SvCUR_set(s->sv, s->cur - SvPVX(s->sv));
-    // TODO: SvPV_shrink_to_cur?
+    if (s->sv) {
+        SvCUR_set(s->sv, s->cur - SvPVX(s->sv));
+        // TODO: SvPV_shrink_to_cur?
+    } else {
+        s->sv = newSVpvn_flags(s->sbuf, s->cur - s->sbuf, s->mortal ? SVs_TEMP : 0);
+    }
+    if (s->setutf8) SvUTF8_on(s->sv);
     return s->sv;
 }
 
 #define fustr_init(a,b,c) fustr_init_(aTHX_ a,b,c)
 #define fustr_reserve(a,b) fustr_reserve_(aTHX_ a,b)
 #define fustr_write(a,b,c) fustr_write_(aTHX_ a,b,c)
+#define fustr_write_ch(a,b) fustr_write_ch_(aTHX_ a,b)
 #define fustr_write_buf(a,b) fustr_write_buf_(aTHX_ a,b)
 #define fustr_done(a) fustr_done_(aTHX_ a)
diff --git a/c/jsonfmt.c b/c/jsonfmt.c
index fe91e29..7fd8859 100644
--- a/c/jsonfmt.c
+++ b/c/jsonfmt.c
@@ -30,7 +30,7 @@ static void fujson_fmt_str(pTHX_ fujson_fmt_ctx *ctx, const char *stri, size_t l
         croak("invalid codepoint encountered in string, cannot format to JSON");
     }
 
-    fustr_write(&ctx->out, "\"", 1);
+    fustr_write_ch(&ctx->out, '\"');
     fustr_reserve(&ctx->out, len);
 
     while (off < len) {
@@ -78,7 +78,7 @@ static void fujson_fmt_str(pTHX_ fujson_fmt_ctx *ctx, const char *stri, size_t l
         }
     }
 
-    fustr_write(&ctx->out, "\"", 1);
+    fustr_write_ch(&ctx->out, '\"');
 }
 
 static const char fujson_digits[] =
@@ -109,7 +109,7 @@ static void fujson_fmt_int(pTHX_ fujson_fmt_ctx *ctx, SV *val) {
     }
 
     if (uv == 0) {
-        fustr_write(&ctx->out, "0", 1);
+        fustr_write_ch(&ctx->out, '0');
         return;
     }
 
@@ -125,10 +125,10 @@ static void fujson_fmt_int(pTHX_ fujson_fmt_ctx *ctx, SV *val) {
 
 static void fujson_fmt_av(pTHX_ fujson_fmt_ctx *ctx, AV *av) {
     int i, len = av_count(av);
-    fustr_write(&ctx->out, "[", 1);
+    fustr_write_ch(&ctx->out, '[');
     ctx->pretty++;
     for (i=0; i<len; i++) {
-        if (i) fustr_write(&ctx->out, ",", 1);
+        if (i) fustr_write_ch(&ctx->out, ',');
         fujson_fmt_indent(aTHX_ ctx);
         SV **sv = av_fetch(av, i, 0);
         if (sv) fujson_fmt(aTHX_ ctx, *sv); /* sv will have magic if av is tied, but fujson_fmt() handles that. */
@@ -136,7 +136,7 @@ static void fujson_fmt_av(pTHX_ fujson_fmt_ctx *ctx, AV *av) {
     }
     ctx->pretty--;
     if (i) fujson_fmt_indent(aTHX_ ctx);
-    fustr_write(&ctx->out, "]", 1);
+    fustr_write_ch(&ctx->out, ']');
 }
 
 static int fujson_fmt_hvcmp(const void *pa, const void *pb) {
@@ -159,12 +159,12 @@ static int fujson_fmt_hvcmp(const void *pa, const void *pb) {
 
 static void fujson_fmt_hvkv(pTHX_ fujson_fmt_ctx *ctx, HV *hv, HE *he, char **hestr) {
     STRLEN helen;
-    if (*hestr) fustr_write(&ctx->out, ",", 1);
+    if (*hestr) fustr_write_ch(&ctx->out, ',');
     fujson_fmt_indent(aTHX_ ctx);
     *hestr = HePV(he, helen);
     fujson_fmt_str(aTHX_ ctx, *hestr, helen, HeUTF8(he));
     if (ctx->pretty > 0) fustr_write(&ctx->out, " : ", 3);
-    else fustr_write(&ctx->out, ":", 1);
+    else fustr_write_ch(&ctx->out, ':');
     fujson_fmt(aTHX_ ctx, UNLIKELY(SvMAGICAL(hv)) ? hv_iterval(hv, he) : HeVAL(he));
 }
 
@@ -173,7 +173,7 @@ static void fujson_fmt_hv(pTHX_ fujson_fmt_ctx *ctx, HV *hv) {
     char *hestr = NULL;
 
     int numkeys = hv_iterinit(hv);
-    fustr_write(&ctx->out, "{", 1);
+    fustr_write_ch(&ctx->out, '{');
     ctx->pretty++;
 
     /* Canonical order on tied hashes is not supported. Cpanel::JSON::XS has
@@ -204,7 +204,7 @@ static void fujson_fmt_hv(pTHX_ fujson_fmt_ctx *ctx, HV *hv) {
     }
     ctx->pretty--;
     if (hestr) fujson_fmt_indent(aTHX_ ctx);
-    fustr_write(&ctx->out, "}", 1);
+    fustr_write_ch(&ctx->out, '}');
 }
 
 static void fujson_fmt_obj(pTHX_ fujson_fmt_ctx *ctx, SV *rv, SV *obj) {
@@ -305,9 +305,9 @@ static SV *fujson_fmt_xs(pTHX_ I32 ax, I32 argc, SV *val) {
     if (ctx.out.maxlen == 0) ctx.out.maxlen = 1<<30;
     if (ctx.depth == 0) ctx.depth = 512;
 
-    fustr_init(&ctx.out, sv_2mortal(newSV(128)), ctx.out.maxlen);
+    fustr_init(&ctx.out, sv_newmortal(), ctx.out.maxlen);
     fujson_fmt(aTHX_ &ctx, val);
-    if (ctx.pretty >= 0) fustr_write(&ctx.out, "\n", 1);
+    if (ctx.pretty >= 0) fustr_write_ch(&ctx.out, '\n');
     r = fustr_done(&ctx.out);
     if (!encutf8) SvUTF8_on(r);
     return r;
diff --git a/c/jsonparse.c b/c/jsonparse.c
index 9e1e16c..8a52b5b 100644
--- a/c/jsonparse.c
+++ b/c/jsonparse.c
@@ -14,19 +14,19 @@ static void fujson_parse_ws(pTHX_ fujson_parse_ctx *ctx) {
     }
 }
 
-static int fujson_parse_string_escape(pTHX_ fujson_parse_ctx *ctx, fustr *r) {
+static inline int fujson_parse_string_escape(fujson_parse_ctx *ctx, fustr *r) {
     unsigned int n, s;
     ctx->buf++; /* '\\' */
-    if (ctx->buf == ctx->end) return 1;
+    if (UNLIKELY(ctx->buf == ctx->end)) return 1;
     switch (*(ctx->buf++)) {
-        case '"': fustr_write(r, "\"", 1); break;
-        case '\\': fustr_write(r, "\\", 1); break;
-        case '/': fustr_write(r, "/", 1); break; /* We don't escape this one */
-        case 'b': fustr_write(r, "\x08", 1); break;
-        case 't': fustr_write(r, "\x09", 1); break;
-        case 'n': fustr_write(r, "\x0a", 1); break;
-        case 'f': fustr_write(r, "\x0c", 1); break;
-        case 'r': fustr_write(r, "\x0d", 1); break;
+        case '"': *(r->cur++) = '\"'; break;
+        case '\\':*(r->cur++) = '\\'; break;
+        case '/': *(r->cur++) = '/';  break; /* We don't escape this one */
+        case 'b': *(r->cur++) = 0x08; break;
+        case 't': *(r->cur++) = 0x09; break;
+        case 'n': *(r->cur++) = 0x0a; break;
+        case 'f': *(r->cur++) = 0x0c; break;
+        case 'r': *(r->cur++) = 0x0d; break;
         case 'u':
             /* (awful code adapted from ncdu) */
 #define INV (1<<16)
@@ -44,8 +44,8 @@ static int fujson_parse_string_escape(pTHX_ fujson_parse_ctx *ctx, fustr *r) {
                 n = 0x10000 + (((n & 0x03ff) << 10) | (s & 0x03ff));
                 ctx->buf += 6;
             }
-            fustr_reserve(r, 4);
             r->cur = (char *)uvchr_to_utf8((U8 *)r->cur, n);
+            if (n >= 0x80) r->setutf8 = 1;
             break;
 #undef INV
 #undef hn
@@ -56,45 +56,41 @@ static int fujson_parse_string_escape(pTHX_ fujson_parse_ctx *ctx, fustr *r) {
     return 0;
 }
 
-static SV *fujson_parse_string(pTHX_ fujson_parse_ctx *ctx) {
-    fustr r;
-    size_t len, maxlen;
-    unsigned char x = 0;
-    fustr_init(&r, newSV(32), SIZE_MAX);
+static int fujson_parse_string_buf(pTHX_ fujson_parse_ctx *ctx, fustr *r) {
+    size_t len;
+    unsigned char x;
     ctx->buf++; /* '"' */
     while (true) {
-        /* Fast path: ASCII, no unescaping needed */
-        len = 0;
-        maxlen = ctx->end - ctx->buf;
-        while (len < maxlen) {
-            x = ctx->buf[len];
-            /* While we always escape 0x7f when formatting, JSON does permit it unescaped */
-            if (x <= 0x1f || x == '"' || x == '\\' || x >= 0x80) break;
-            len++;
-        }
-        if (len == maxlen) goto err;
-        fustr_write(&r, (const char *)ctx->buf, len);
-        ctx->buf += len;
-
-        /* Slow path */
-        if (x == '"') {
+        fustr_reserve(aTHX_ r, 4);
+        if (UNLIKELY(ctx->buf == ctx->end)) return 1;
+        x = *ctx->buf;
+        if (UNLIKELY(x == '"')) {
             ctx->buf++;
-            SvUTF8_on(fustr_done(&r));
-            return r.sv;
-        } else if (x == '\\') {
-            if (fujson_parse_string_escape(aTHX_ ctx, &r)) goto err;
+            return 0;
+        } else if (UNLIKELY(x == '\\')) {
+            if (fujson_parse_string_escape(ctx, r)) return 1;
         } else if (x >= 0x80) {
-            len = isC9_STRICT_UTF8_CHAR(ctx->buf, ctx->end);
-            if (len == 0) goto err;
-            fustr_write(&r, (const char *)ctx->buf, len);
+            if (UNLIKELY((len = isC9_STRICT_UTF8_CHAR(ctx->buf, ctx->end)) == 0)) return 1;
+            memcpy(r->cur, ctx->buf, len);
+            r->cur += len;
             ctx->buf += len;
-        } else {
-            goto err;
-        }
+            r->setutf8 = 1;
+        } else if (x >= 0x20) {
+            *(r->cur++) = x;
+            ctx->buf++;
+        } else return 1;
+    }
+}
+
+static SV *fujson_parse_string(pTHX_ fujson_parse_ctx *ctx) {
+    fustr r;
+    fustr_init(&r, NULL, SIZE_MAX);
+    if (fujson_parse_string_buf(aTHX_ ctx, &r)) {
+        if (r.sv) SvREFCNT_dec(r.sv);
+        return NULL;
+    } else {
+        return fustr_done(&r);
     }
-err:
-    SvREFCNT_dec(r.sv);
-    return NULL;
 }
 
 /* Validate JSON grammar of a number, increments ctx->buf to the end of the
@@ -180,8 +176,12 @@ err:
 
 static SV *fujson_parse_obj(pTHX_ fujson_parse_ctx *ctx) {
     HV *hv = newHV();
-    SV *key = NULL;
     SV *val;
+    char *keystart;
+    UV keyhash;
+    fustr key;
+    fustr_init(&key, NULL, SIZE_MAX);
+
     ctx->buf++; /* '{' */
     fujson_parse_ws(aTHX_ ctx);
     if (ctx->buf == ctx->end) goto err;
@@ -189,9 +189,11 @@ static SV *fujson_parse_obj(pTHX_ fujson_parse_ctx *ctx) {
     while (true) {
         /* key */
         if (*ctx->buf != '"') goto err;
-        if (!(key = fujson_parse_string(aTHX_ ctx))) goto err;
-        /* TODO: Use precomputed hash */
-        if (hv_exists_ent(hv, key, 0)) goto err;
+        if (fujson_parse_string_buf(aTHX_ ctx, &key)) goto err;
+        keystart = fustr_start(&key);
+        if (key.setutf8) keyhash = 0;
+        else PERL_HASH(keyhash, keystart, key.cur - keystart);
+        if (hv_common(hv, NULL, keystart, key.cur - keystart, key.setutf8, HV_FETCH_ISEXISTS, NULL, keyhash)) goto err;
 
         /* ':' */
         fujson_parse_ws(aTHX_ ctx);
@@ -201,9 +203,9 @@ static SV *fujson_parse_obj(pTHX_ fujson_parse_ctx *ctx) {
 
         /* value */
         if (!(val = fujson_parse(aTHX_ ctx))) goto err;
-        hv_store_ent(hv, key, val, 0);
-        SvREFCNT_dec(key); /* TODO: can reuse buffer */
-        key = NULL;
+        hv_common(hv, NULL, keystart, key.cur - keystart, key.setutf8, HV_FETCH_ISSTORE|HV_FETCH_JUST_SV, val, keyhash);
+        key.cur = keystart;
+        key.setutf8 = 0;
 
         fujson_parse_ws(aTHX_ ctx);
         if (ctx->buf == ctx->end) goto err;
@@ -213,10 +215,11 @@ static SV *fujson_parse_obj(pTHX_ fujson_parse_ctx *ctx) {
         fujson_parse_ws(aTHX_ ctx);
     }
 done:
+    if (key.sv) SvREFCNT_dec(key.sv);
     ctx->buf++; /* '}' */
     return newRV_noinc((SV *)hv);
 err:
-    if (key) SvREFCNT_dec(key);
+    if (key.sv) SvREFCNT_dec(key.sv);
     SvREFCNT_dec((SV *)hv);
     return NULL;
 }
diff --git a/t/json_parse.t b/t/json_parse.t
index da225bf..be76e31 100644
--- a/t/json_parse.t
+++ b/t/json_parse.t
@@ -49,6 +49,7 @@ my @error = (
     '{"":1,}',
     '{,}',
     '{"":1,"":2}',
+    '{"ë":1,"ë":1}',
 );
 for my $s (@error) {
     ok !eval { json_parse($s); 1 };
@@ -70,10 +71,10 @@ sub str($in, $exp) {
     utf8::encode(my $str = $in);
     my $out = json_parse($in);
     is $out, $exp, $str;
-    ok utf8::is_utf8($out);
+    ok utf8::is_utf8($out) || $out =~ /^[\x00-\x7f]*$/;
     $out = json_parse($str, utf8 => 1);
     is $out, $exp, $str;
-    ok utf8::is_utf8($out);
+    ok utf8::is_utf8($out) || $out =~ /^[\x00-\x7f]*$/;
 }
 str '""', '';
 str '"hello, world"', 'hello, world';