until you can look into your problem. you may want to start mixing down some of those individual tracks to eliminate some heavy plugins.
the key here is to mix down the original track before you've tinkered with it at all as well.
that way if you ever need to go back (which you can't do after you've mixed down a track and reinserted it), you can just go back to the original.
saves TONS of processing power.
every now and then I'll end up with a mix that will completely rape my computer for no good reason. it'll go from 40% processing power to major slug after adding 2 basic EQ plugs.
makes me mental when that happens. so I know what you're going through.