Well security software definately can slow your PC down a bit as they all need services running in the background that take away Ram. Usually a memory upgrade can help alleviate that. Can I ask what Operating system you are running and a bit more info about your computer specs like processor type/speed, Ram. Other things that can slow do your computer are things like "bundled apps" that include things like tool bars, free little programs that are advertisement driven and such. Also if your hard drive space is getting low then that can slow the PC down too. You can try running a disk cleanup to clean out old temp files and a defrag to help speed it up and be sure that your computer does not have an underlying spyware or virus infection despite having all that security software.