I have had a lot of lag - though I talked to my local computer shop and they're ordering the parts to upgrade my PC optimally - but I brought it in so he could make sure he could get all the right parts for it. Well, I had a lot of dirt built up from smoking, clogging heat sinks, to the point that he suggested it wasn't safe and gave a quick clean. I came home and the thing is already lagging a lot less - almost not at all. If you have any of that, a professional cleaning might fix a lot of the problems.
