While somewhat overdue, I wanted to clarify the discussion of latency compensation missing in Logic 7 but promised for a future update.
Latency compensation describes host software's ability to calculate the
lag introduced by some effects and instruments, particularly those
dependent on external DSP hardware. As Cris 'atariboy'
has pointed out, Logic does have latency compensation, just not for
buses. That's a big omission, obviously, since a bus is often exactly
where you'll put an effect. There's been some discussion of this issue
on the Sonikmatter community; I'm having trouble with direct links to those boards so try searching for "latency compensation."

(Read on for more thoughts on Logic and performance . . .)

Apple is lagging on the Mac behind MOTU's Digital Performer
in this respect, and lacks DP's more robust support for Digidesign
systems and dynamic CPU management. Some of these are problems with a
niche market — many users don't have setups that require bus-based
latency compensation and don't use Digidesign hardware. Dynamic CPU
management is another matter: DP is very smart about letting go of CPU
cycles on inactive channels and effects, while inactive Environment
objects can suck up CPU without even having an active track.

Apple is fixing at least the latency compensation issues. I hope it
will tweak other performance issues, as well, and I'm disappointed
they're planning to charge a "nominal fee" for the
currently-unavailable update. I hope they deliver this soon, and that
they really mean nominal. Don't get me wrong: Logic is a superb audio
application and delivers an incredible value as far as its instruments
and effects. I would like to see Apple address these other issues,
however, partly so that Logic gets its due credit and Logic users get
the app they deserve.