It isn't. Most likely, you have to clean it out. What OS are you running?
First of all, get CCleaner
, and run that, gets rid of temp files and a lot of other junk. Disregard the registry cleaner.
Did you run a virus and/or spyware check lately? Get Malwarebytes
and run that.
Go to the run command, type in msconfig
, and go to the startup tab. Unless you know what the program is and need it, keep it checked. All the others, uncheck. You can always re-enable them.