It sounds like some malware/spyware. Something is probably running that just advertises itself and its affiliates. Things like this tend to take up quite a bit of memory because they are constantly sending and receiving data. The data they receive is usually instructions, to the program(s) in question, on what to do next. Have you tried Spy-bot or Malwarebytes? They may find the problem (likely) and fix it. Before running these, I would run C Cleaner to make not only the scan go a touch faster, but that also sorts out a lot of problems. Especially with dead files in the registry.|
Also when installing these you may want to read carefully what each step is doing so you won't get unwanted bundle software, which may further slow down the system, when you install.
"A woman is a woman, but a good cigar is a smoke"
- Rudyard Kipling