Restart your computer. I call it the 100% CPU Usage Bug. After your computer hits 100% Usage, you need to restart your computer, and everything will be better. It could be just chrome, but I don't think any background programs would be causing it, because your only running Chrome. Background programs would only wash away RAM, and CPU too if they're running. I have the same problem. Chrome doesn't waste a lot of CPU Usage if your not loading anything (obviously), but just a lot of RAM.