1) Install the OS properly with the latest drivers all again from this guide:
ASUS G75VW Clean Install Guide2) Upgrade to an SSD + HDD combo, you have to slots. I have the OS + apps + games installed on the SSD and my other files (music, videos, pr0n, etc) / software installation /setup files on the HDD and unleash the true power of your computer.
3) Uninstall that piece of crap antivirus and install the best antivirus for system performance, either ESET NOD32 or ESET Smart Security and watch your system get a turbo boost in performance as if you had no AV installed yet still secure as heck
Your major bottleneck is the crappy HDD along with other tips I told you
Don't buy a Shelby then equip it with a lame transmission and call it slow! know your ride before you complain