Wow, ignore everybody...
Your hard drive will only impact performance in the event it's loading information directly from the hard drive into RAM, then to your CPU. So unless you're opening programs and files stored on your hard drive, it will have no impact on how quickly your web pages load.
Your CPU's performance can potentially deteriorate over time, but unless you notice an all-around, very-noticable performance hit I would rule out the CPU being the culprit.
If you're experiencing delays in your internet service, you may want to contact your ISP and ask them why you are experiencing such poor service.
You may also want to consider when the last time any maintenance was done on your computer. Do a Google search for CCleaner and install it, and run it. It will analyze your computer for useless information and fix your system registry.
Other non-third-party tools you can use that come with Windows are Disk Cleanup, CHKDSK and Defragmentor. For Disk Cleanup, go to:
Start -> Accessories -> System Tools -> Disk Cleanup.
Do a scan and cleanup your C: drive.
Disk Defragmentor can also be found in the same directory.
To perform a CHKDSK, there are two ways you can do it:
1) Start -> Computer -> Right-Click C: -> Properties -> Tools -> CHKDSK -> Schedule a Disk Check and restart your computer.
2) Start -> Command Prompt (Run as admin) -> Type in "CHKDSK C:" and press enter
If you have a ton of programs running in the background, it will also slow down your system considerably. You may want to reduce the number of background tasks by going to:
Start -> Run -> Type in "MSConfig"
You want to check in the "Services" and "Startup" options. Please do not turn off any services until you do some research to find out whether or not your system actually needs it to run properly.
You may also want to check the physical condition of your system as well. If it's dirty, airflow is restricted which will cause deficient cooling. If your CPU is not properly cooled then it will get hot. When it gets hot, your CPU performs what is called "Throttling": It will slow itself down to prevent any potential thermal damage.