It's not the filesystem access that is slow. It is that the current source code storage format reads the file character by character, looking for the terminating !, and doing utf-8 conversion the whole way. 95% of the time in a MC snapshot is spent in testing the source file characters for the terminating ! character. I imagine you do much more in bulk rather than character by character. The format of the .sources file is horrible for access speed.
Oh, right! I forgot about that. :) Yeah, should be quite a bit faster, I'm just answering String objects that are sitting in memory. The measurements will be interesting.
But again, I take it from your comment that you're actually finding the speed of the traditional setup to be a problem? If so, then yeah, it'd make a good marketing point.
thanks again,
-C