Don't replace spaces with \s. \s would be slower since it matches spaces, tabs, carriage returns (I think) and line feeds, and even more if it's a unicode string. "\x20", "\040", "\", and "[ ]" work. (I wonder if the last is slower than the others. I'll Benchmark later.)

You've also added useless captures. Don't use (...) (which incures a speed penalty), use (?:...).