I had been looking for this thread, trying to answer it, but I couldn't find it. Thanks for bumping it. :)
Actually, the weird thing is that the values you told me do reflect that it's running plainly slow. I find it weird because your hardware should, by all accounts, be better then mine (I have an AMD Athlon64 X2 2.2 GHz, and a GeForce 7300 GS, and am also running a 32 bit OS), and it's running perfectly fast for me, even with the screen full of crops.
What you write about it running fine "for like 5 seconds, then the fans start like crazy and everything slows down", does seem indicative to me of a clogged air channel in your laptop. (It is a laptop, right? I assumed so the you said you have a GeForce M graphics card.) Jorb's laptop also had that kind of problem, where the vent was clogged with dust, and it, too, would run fine in the beginning and then slow down with the fans running like crazy. After I disassembled it and declogged the vent, it ran perfectly well. My theory is that the CPU and/or GPU, sensing that they were too hot, scaled down their operating frequencies in order not to overheat. I know it kinda seems like cheating to blame it on the hardware, but it does sound like that to me.