Why is my task manager saying 50% performance when im only on Desktop?

You mean the CPU performance is up to 50%? that could mean you have maliscious software running in the back ground. Boot to safe mode and check if you still have it there. Also try disabling the startup files to stop that program fom running when you turn the PC on.

You might have some hidden applications running in background. Switch to the Processes tab in Task Manager and see what's running. Also, it could be a spyware problem your'e facing... Try installing antivirus and antispyware software and keeping them up to date. I reccomend NOD32 as antivirus. :)