So far I haven't had too much trouble running the Focusrite Fore Suite TDM. I have run the software on an Apple G5 desktop that runs with a Pro Tools HD system and I haven't had any problems running a few of these at a time. However, if you are running a Pro Tools LE system, I would bet that you would find that this plug-in would take up a good amount of processing power because it does have a lot going on at once. This being said, if you find yourself having trouble running a few at a time, I would try to use each plug-in individually if you are only using part of the plug-in as this will save processing power.
I've only been using the Focusrite Fore Suite TDM for a few months but I've definitely been impressed in this time. While I'm not a huge fan of Focusrite hardware, they have done quite a good job with this plug-in. All of the plug-ins are quite clean sounding, but I probably like using the compressor and the de-esser the best as I find these to be the most useful. At $400 USD, this isn't a bad deal considering that you are getting a bunch of different effects within the channel strip, but still isn't all that great of a deal. If you are looking for a channel strip that has all sorts of dynamic processing and EQ, the Focusrite Fore Suite TDM is an option that should be explored.