diff --git a/programs/escape.c b/programs/escape.c
--- a/programs/escape.c
+++ b/programs/escape.c
@@ -23,12 +23,41 @@
 #include "common.h"
 #include "escape.h"
 
+/* ESCAPE-TRACE (scripts/escape_trace.diff, instrumentation only): append one
+ * line per call to /tmp/escape_trace.log with the number of examined
+ * characters of each class and of buffer growths. Changes no result. */
+static void
+escape_trace (const char *func, int sp, int hi, int pl, int ct, int grow)
+{
+  FILE *f = fopen ("/tmp/escape_trace.log", "a");
+  if (!f)
+    return;
+  fprintf (f, "ESCAPE-TRACE %s in=%d special=%d high=%d plain=%d ctl=%d grow=%d\n",
+           func, sp + hi + pl + ct, sp, hi, pl, ct, grow);
+  fclose (f);
+}
+#define ESCAPE_COUNT(c, sp, hi, pl, ct)                                      \
+  do                                                                         \
+    {                                                                        \
+      if ((c) >= 127)                                                        \
+        hi++;                                                                \
+      else if ((c) == 34 || (c) == 39 || (c) == 38 || (c) == 60 || (c) == 62 \
+               || (c) == 96 || (c) == 123 || (c) == 125)                     \
+        sp++;                                                                \
+      else if ((c) >= 20)                                                    \
+        pl++;                                                                \
+      else                                                                   \
+        ct++;                                                                \
+    }                                                                        \
+  while (0)
+
 char * ATTRIBUTE_MALLOC
 htmlescape (const char *restrict src, const int cp)
 {
   int len;
   char *dest, *d, *end;
   unsigned char *s;
+  int nsp = 0, nhi = 0, npl = 0, nct = 0, ngrow = 0;
   if (!src)
     return NULL;
   len = strlen (src) + 10;
@@ -46,7 +75,9 @@
           d = dest + off;
           *d = 0;
           end = dest + len;
+          ngrow++;
         }
+      ESCAPE_COUNT (*s, nsp, nhi, npl, nct);
       switch (*s)
         {
         case '"':
@@ -97,6 +128,7 @@
       s++;
     }
   *d = 0;
+  escape_trace ("htmlescape", nsp, nhi, npl, nct, ngrow);
   return dest;
 }
 
@@ -107,6 +139,7 @@
   char *dest, *d;
   BITCODE_TU tmp = wstr;
   BITCODE_RS c;
+  int nsp = 0, nhi = 0, npl = 0, nct = 0, ngrow = 0;
 
   if (!wstr)
     return NULL;
@@ -123,7 +156,9 @@
           len += 16;
           dest = realloc (dest, len);
           d = dest + off;
+          ngrow++;
         }
+      ESCAPE_COUNT (*wstr, nsp, nhi, npl, nct);
       switch (*wstr)
         {
         case 34: strcat (d, """); d += 6; break;
@@ -145,5 +180,6 @@
         }
     }
   *d = 0;
+  escape_trace ("htmlwescape", nsp, nhi, npl, nct, ngrow);
   return dest;
 }