[elibarzilay]

In general, 3m is performing very well, much better than the conservative collector plt used to use by default (the boehm gc). As for the jit: many of the benefit of the jit are irrelevant in Arc since it doesn't use mzscheme modules; this is in addition to using an old mzscheme version, when the jit was rather new -- many many improvements were done since then.