Return of Reckoning

I've been playing on this server for years. The game has ran fine on my pc with no issues. But recently maybe about a month ago when i play this game my pc fans run alot and fast. I checked the task manager and it now shows high CPU usage for a few seconds when i first pull the task manager up and then it drops down to normal. But when i play the game again, the fans spin very fast again and CPU usage goes right back up. Any help or suggestions please thanks