I am using windows 7, and lately it started slowing down. Looking at the task manager I see that my CPU is running between 60% to 95% usage.
After turning down every process listed, I was still getting over 60% of CPU usage.
What else should I try?
Open Task Manager
Click on Processes
Click on Show Processes from all users(This requires you to be a computer administrator)
Click on CPU at the top to sort by CPU.
This will allow you to see what is causing the CPU usage, you may be infected with Malware if it is being run by the system account(shows blank under user name). I recommend running a full malware scan if this is the case.
Task manager may not show DCP or System Interrupts hogging CPU cycles, open a run command and type
resource monitor will open, go to the cpu tab, the offending process will float to the top of the list after a few seconds.