Seems like the VC++ string::push_back is pretty terrible

SoftwareOcclusionCulling/CPUT/CPUT/CPUTConfigBlock.cpp

@@ -87,18 +87,30 @@ static const char *FindLast(const char *start, const char *end, char ch)
 static void AssignStr(cString &dest, const char *start, const char *end, _locale_t locale)
 {
 	dest.clear();
-	dest.reserve(end - start); // assume most characters are 1-byte
+	if (end <= start)
+		return;
+
+	static const int NBUF = 64;
+	wchar_t buf[NBUF];
+	int nb = 0;
+
+	size_t len = end - start;
+	size_t initial = len + 1; // assume most characters are 1-byte
+	dest.reserve(initial);
 
 	const char *p = start;
 	while (p < end)
 	{
-		wchar_t wc;
-		int len = _mbtowc_l(&wc, p, end - p, locale);
+		int len = _mbtowc_l(&buf[nb++], p, end - p, locale);
 		if (len < 1)
 			break;
 
-		dest.push_back(wc);
 		p += len;
+		if (p >= end || nb >= NBUF)
+		{
+			dest.append(buf, nb);
+			nb = 0;
+		}
 	}
 }