Occasionally MT uses a lot of CPU on my computer. It comes and goes - I haven't figured out what brings it on or when it leaves. It is not related to busy times in the market. Currently (10:15 AM PST on a Tuesday), Medved Trader is using about 85% of my laptop's CPU. Normally it uses about 10 or 15% or so.
I don't know where to find the version I'm running currently, but it is the latest one I was prompted to download (a day or two ago, I believe).