Well, arch/bazaar/bzr are much slower than git, but OTOH, they have a lot of room to improve
(unlike git, which has to take a lot of more pain to improve, since it is so far up the curve
already), and AFAIK, Canonical is working hard on bzr.
But the real timehog issue when converting from CVS to anything else less stupid (bzr, hg,
git, monotone, whatever) is that you look at the resulting history, and go YUCK!
One never really looks at history in CVS. One tries to ignore it as best as one can, because
it is ugly as all heck. That's not what happens when you get better tools where the history
and branching is actually useful for something. So, suddenly, you ARE looking at all that
horrible snapshot of your past, and you cannot easily ignore its existence anymore. It is
cleanup time, and that has to be done mostly manually, which takes time.
cvsps is a lifesaver helper, but it doesn't do nearly well enough to produce a very clean
history, especially when you have lots of branching.