That doesn't appear to make sense, and I don't mean that as an insult or anything.
Under energy saver preferences on older models, you can set your computer to low speed to save power, high speed, or auto. Auto will push the CPU at full speed as it's needed.
Try going into your applications folder, then utilities and running Activity Monitor. Some good processor/memory usage in that app.
Games all have different means of showing you the frames-per-second your system is achieving, you'd have to look it up in per-game.