Everytime I attempt to run Chaos Arena (I'm trying to run CA2 or CA5, depending on the character), the dungeon lags like crazy after about the first 2-3 minutes. I know my PC isn't even close to what I would consider a "gaming PC" but it exceeds the minimum requirements for the game. Are there any tips on what I can do to at least make it so I the lag isn't so bad?

My PC's stats are as follows:
- Intel Core2Duo T5550 CPU (1.83GHz)
- 3GB DDR2 RAM
- Intel 965 Express Graphics (384MB graphics RAM)
- Windows 7 Ultimate (32-bit)

Other software that runs while playing:
- IOBit Game Booster (v2.3)
- Avast Internet Security (v6.0.1000)

I've also tried the following to try to resolve the issue:
- Disabling internet security software
- Running game graphics on lowest settings
- Running the game on a fresh install of Windows 7 with no other installed software (other than Game Booster)


I know the graphics are kinda weak, and a laptop isn't the best to play on, but the rest of the game runs fine. It's only Chaos Arena that lags so bad. Also, I've heard that I might be able to change the enemy sprites to something that doesn't require as much graphics power (like a nipperlug or something), but I don't know how to do that.