is RELENG_5 Borked?

I upgraded my Dell Inspiron 7500 to RELENG_5 and have been seeing all sorts of 
problems.
Previously it was running 5.3 beta7 and seemed happy with that.

the symptoms..
boot to single user succeeds.
however if the filesyste,s do not need cleaning  (?)
it will freeze solit part way through going to multi-user..
usually just after printing "preserving vi files" (or whatever the
actual message is).

However if the filesystems DO need checking.
it says that te filesyste, wil be checked in background,
and that background fsck will be started in 60 seconds, and teh boot succeeds
all the way to multi user mode.

Once there, though I have to live with the slowdown of the fsck running...

Even before fsck starts however, everything appears VERY slow. The mouse
reponds slowly and jerkily.

This was all not true with 5.3B7 so it's a recent change..