GBoost is an easy-to-use tool that aims to optimise your PC's performance with a single click.
The program works by temporarily closing unnecessary apps that may be sapping your system's resources. So this might include instant messaging tools, music players, browsers, webcam software, mobile phone-related services, and many other background processes. It can disable Windows Aero graphics, and even turn off some antivirus tools.
That last idea in particular sounds like a step too far, but don't worry, you're able to choose what GBoost will do (and it won't turn off security apps by default: you must specifically request this). So clicking the "Boost" button will only turn off processes you've confirmed that you don't need.
And even if you do get this wrong initially, and accidentally disable something important, it doesn't really matter. GBoost makes no permanent changes. If the boost process causes some problems, just click Restore, or reboot, and your system will be back to normal.