The Bomb Factory LA-2A Compressor won't take up much processing power as I find that I can run a good amount of them at a time. I am currently running the plug-in on a Mac Book Pro that has a 2.2 Ghz Intel Core 2 Duo processor and 4 GB of RAM. I run the plug-in in Pro Tools LE 7.4 that runs with a Digi002R audio interface. I'm able to run a bunch of these at a time if I want so as long as you have a decent system you shouldn't have any problems with it.
While everything about using the Bomb Factory LA-2A Compressor is easy, I'm not a huge fan of this plug-in as a whole as I don't think that the sound quality does the original LA-2A justice at all. It has a decent sound but doesn't sound nearly as good as many of the other compression plug-ins that I use like the URS Classic Compressor and Digidesign Smack. There is also a much better emulation of the LA-2A out there made by Universal Audio that sounds much better than this one does. So if you are looking for an emulation of the LA-2A or simply a good compression plug-in, I would look elsewhere.