Feel free to spend your money on a new graphics card if you wish but I would put money on the fact that it won't solve your problem. Often starting from scratch and re-installing is the best way to solve these sort of problems. You mentioned having anti spyware, anti malware etc. These sort of programs can often be some of the worst culprits for slowing a computer down, Norton in particular is one of the worst pieces of bloatware that I have ever seen! If you have Windows 10 it has very good anti virus built in in the form of Windows Defender and if you have Windows 7 you can download Microsoft Security Essentials for free which is basically the same thing. You really don't need any more than this to keep you safe.