RTAS plugins using way too much CPU?

[DSwartz]

For some reason when I opened up Pro Tools today, my plugins seemed to be taking up inordinate amounts of CPU power. Any session I try to play with more than one or two plugins running will overload the CPU after a few seconds. Sessions without plugins don't seem to have any problems. Now, I have a pretty fast computer and before today I was running 10-20 plugins at a time with no problems, so it seems like there definitely an issue here. The only thing I've done recently that I think may have caused this is upgraded Quicktime to version 7.4.5. I didn't think updating something other than Pro Tools or the operating system would cause problems, but it may have caused this. What do you guys think?

Also, there seem to be "spikes" in the CPU usage according to the CPU meter in Pro Tools. While the part of the CPU bar that is solid green (I assume this is average CPU usage) never gets above 25% or so, the green line after the solid green bar (which I assume is peak CPU usage) spikes to 75% to 100% usage every couple seconds. I dunno if this is relevant or not but it seems worth mentioning.

So, after further messing around, I found out that if I check the "Ignore errors during playback/record" option, it seems to fix the problem...the session plays back fine, and I don't hear any clicks or pops. Interestingly, the peak CPU usage seems to stop spiking after I check this option as well. Still, I'd like to find a way to get it to work without having to do this, since it seems like keeping this option checked has the potential to reduce the playback/recording quality, so if this information clues anybody in to what the problem is, please post your thoughts! Thanks!

Here are my system specs:

2.2 ghz Core 2 Duo Macbook Pro with 2GB RAM running Mac OSX 10.4.11
Pro Tools LE 7.4 with Mbox2 (plugged into the left USB port, of course)
External hard drive connected via Firewire 800
iLok attached to right USB port