I thought I'd share the method I use to resolve those pesky lag spikes. I don't know if it'll work for you, but I thought I'd put it out there just in case. It's pretty simple: when you get a lag-spike, go into slow-motion by pressing ALT + left arrow or using whatever key is designated by your keymap. Then, after 5 or so seconds, press ALT + up arrow, and (for me, anyway) the lag spike is resolved. Hope this works!
uhm, im not sure if i understand right but my lag spikes last way less time than any ammount of slowmotion would do, alone activating slowmotion takes longer than a lagspike and no my pc is not overpowered its 4+years old.^^
If youre talking about the freezes that occure every once in a while, ive found that pressing j (stop dynamics) and then pressing it again does the same thing you describe.