Format is the last resort. First thing you need to do is to go into your Control Panel.
Start Menu the Control Panel should be there. When that loads up click on Add/Remove Programs.
When that pops up make sure to remove the entries that you no longer want or need.
From there Start Menu>Run. Type in msconfig in the run window. This bring up another window.
This window click on the Startup tab and uncheck all entries that are not necessary. It is recommended to leave Firewalls, and Anti-Virus applications running.
If you are unsure then post some of the entries and we can help you sort them out.
I do not accept support questions via EMail, PM, IM or my G+ page!
Phone: LG Optimus G Pro
Running: Stock JB from LG with Nova Launcher