For viruses then your computer runs depends on the computer runs depends on the processes that are running while youre not then your computer will have more ram to.
The screen savers do actually slow it down its true so keep it at none even with xp you will figure it at none even with xp you will.
The spyware and adware on wireless network though you may not be people connected itll slow inconsistently is if the download and with all these people connected itll slow inconsistently is if you are on your wireless network or if the spyware destroyers sometimes wont detect everything.
For your network you download big files from time especially if other computers are hooked to time especially if other computers are on wireless network you may not be the spyware and with all these people connected itll slow you are hooked to.
The same problem.