The Celtic Kane JavaScript Benchmark "Array" test can be sped up 19% by using the return value from add() to avoid an extra hash lookup for contains(), and by storing some strings in function-scope static UString variables instead of as constant strings used to make new UStrings every time. These issues mainly affect the Array "join" and "toString" operations, which unfortunately seem to make up the vast majority of time on this benchmark.
Created attachment 16509 [details] patch implementing these two optimizations
Comment on attachment 16509 [details] patch implementing these two optimizations ooh, nice and simple