There are various paths you can take in order to improve the performance of your computer. The problem with browsing speed may relate to your Internet connection speed.
If you want to increase the performance of your computer you will need to uninstall all applications you are not using with a tool like CCLeaner. Clean obsolete registry keys with the very same tool and optimize various settings with an application like WinXP Manager (for Windows XP operating system) or Windows 7 Manager for Windows 7.
These are the best tools to increase system performance through applying various tweaks, in my opinion.
