1. In Explorer, through Folder options > View tab, check the following: Always show icons, never thumbnails.
2. Use ShellExView or Autoruns to disable explorer addons in any.
3. Disable unwanted start-ups through msconfig or freeware WinPatrol.
3. Here is a short video showing how to find out the root cause CPU consumption issues on Windows 7, Vista, Server 2008 and higher operating systems with Xperf, from Technet.