[NOT REALLY SCRIPTING] What's a good computing power budget? [closed]

The question is a bit self-explanatory. What's a good power budget to make sure your game doesn't lag? In case you didn't know you can press F9 in game to see useful statistics, This includes computing power usage.

When i found out about this useful feature i checked in my own game, 456 MB of computing power usage. Then i thought to myself "Is this really that much?", Eager to found out if it was i decided to check some popular games.

To my surprise used Phantom Forces only about 436 MB of power usage.

Now here's the part i need help with?

Are there any good optimization tips? Could i maybe reduce some of the graphics for better performance?