gcc-2.95.3's ostringstream is O(N^2).

See also http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=92524
for how Debian fixed it (essentially the same way).

See also http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16401
for a similar problem in gcc-3.4.1.

Here's a trivial fix:

diff -u -r gcc-2.95.3/libstdc++/sstream gcc-2.95.3-mec-1/libstdc++/sstream
--- gcc-2.95.3/libstdc++/sstream	2000-12-04 12:03:42.000000000 -0500
+++ gcc-2.95.3-mec-1/libstdc++/sstream	2006-03-03 18:39:59.000000000 -0500
@@ -106,7 +106,7 @@
 	  if (c != EOF)
 	    {
 	      streamsize old_stream_len = stream_len;
-	      stream_len += 1;
+	      stream_len = 2*(stream_len+1);
 	      char_type* new_stream = new char_type[stream_len];
 	      memcpy(new_stream, stream, old_stream_len);
 	      delete[] stream;