Just popping this here as I have had this a few times. Have you ever had your desktop icons flash and if you check explorer.exe its using high CPU. If so try:
Step 1. Delete the Icon Cache
Save the following as a batch file on your desktop and run it as admin:
cd /d %userprofile%\AppData\Local\Microsoft\Windows\Explorer
attrib –h iconcache_*.db
del iconcache_*.db
start explorer
pause
Step 2. Tweak the Registry
Try setting these two reg keys to zero:
HKEY_CURRENT_USER\Control Panel\Desktop:ForegroundFlashCount
HKEY_CURRENT_USER\Control Panel\Desktop:ForegroundLockTimeout
Step 3. Switch of Indexing
Run either of these commands (as admin) to stop or suspend windows indexing
sc config cisvc start= disabled
sc config cisvc start= demand