Spybot, is on the machine, and will do nothing. It does not have the capabilities to remove anything other than cookies and related stuff... It cannot remove any of the top 200 infestations... From what I have seen with a great number of client computers, I assume spybot is useless
Did you use Avira or Avast, and then SpySweeper, SuperAntispyware, MalwareBytes, or the others listed in the eight steps?
I see Symantec Norton, and SpyBot. They are not adequate to detect the sorts of evils that might be slowing down your computer.
I suggest you try the ones mentioned above, then let us know what they removed...
We will also need to know your computer brand and model, age, power supply, operating system, and memory configuration. Also, do you have any red or yellow flags in your Device manager Those are critical to developing an analysis of your system.
Slow downs are often caused by infestations, by failing hard drives, by inadequate memory, and by software improperly installed.