PCs only have to do as much as you tell them. If you read your windows docs, you can actually tell windows to use a game as your shell, instead of explorer.exe (or is it systray?). This will enhance some games performance by 75%, especially if you are in a limited ram environment. PCs are only as "inefficiant" as the user employing them.
STAY RIGHT WHERE YOU ARE, GET OUT OF THAT BED AND GET DOWN ON THE FLOOR, GET OUTSIDE RIGHT NOW, RIGHT HERE: GET DOWN ON THE CEMENT, I DONT CARE IF YOU'RE NUDE, GET DOWN ON THE CEMENT, I DON'T CARE IF ITS FREEZING! WHERES THE DRUGS, WE KNOW YOU GOT THE DRU