Rylar22, first let me say I experienced the same as you did with 3.3.5. My CPU resource consumption went pretty high and a lot of RAM was being used and/or swapped to disk.
I do, however, not have decent hardware on the system I was testing with, and I had not played much with previous releases so I concluded that the high resource consumption had to be related to my hardware (and I still think it is to a high degree). I also started a related thread on Intel GPU performance. I should note that those GPUs are known to perform badly because of their lack of dedicated memory - having to share memory for graphics processing with RAM means a lot of front side bus bandwidth gets dedicated to memory management, transfers take considerably longer than on dedicated GPU RAM, and when there is much FSB bandwidth in use, less remains for other concurrent processes - as well as for offloading calculations to the CPU, which even more so reduces available FSB bandwidth and slows down GPU calculations (but then, being directly mounted to the GPU instead of being an add-in card makes things faster again, but not enough to compensate). For office work this doesn't matter at all, and not that much for 2D games, but it sure does matter for 3D games like MegaGlest is one.
But then, based on what you wrote, you are probably not actually using a shared memory GPU but some dedicated one. And, more importantly, you are comparing how two different versions perform, the old one of which you say performed good, and the new one which does not. I think this should make it unnecessary to further inspect your hardware for now (other than for determining the reasons of the slowdown if it was unique to your system setup), though it would still be of interest to me.
I can confirm that on Ubuntu 10.04, which I run, too, the 3.3.5 release was rather slow and resource hungry. Luckily this has improved measurably since (in development builds), and while the game still increases my overall CPU load to up to 100% (of 200% possible on this dual core system), this is less than before, and memory resource consumption has decreased a lot (no more than 512M now), and at the same time, FPS has increased by about one third over 3.3.5.0 for me.
I think there will soon be a 3.3.5.1 (actually this may get renamed to 3.3.6 instead since it also introduces new features) which fixes this and several other issues. Until then, there will be at least one more alpha release (probably sometime tonight in terms of central US time), so I recommend you give those a try - or wait for the next release/bug fix (which may take some more weeks - and that's just my personal guess, not being one of the core developers).
