Random FPS Drops and Flashing

[FSMuseum 39]

Okay, this is probably a pretty common or easy to fix problem but I cant find it anywhere else, so, here goes.

My first issue is random FPS drops. My computer specs are under my profile pic. Usually, the highest FPS I see is about 30 - 35 FPS for about 10 - 60 seconds or so, then it drops about 50 - 80% to around 5 - 15 frames, then it will slowly recover at about 2 FPS every 3 - 5 seconds, until its back at 30 or so, then about 10 - 60 seconds later it will happen again. I have FSX settings and CFG set up at per Nick N's guide over at simforum based on my hardware and tweaked with ******* Bojotes tweaker. I only see this issue with my addon aircraft (PMDG NGX and FSLabs Concorde), not default, and only when doing a real flight, not just flying around for fun, though testing is ongoing.

My second issue is weird graphics flashing. Anytime I look around in any plane I will sometimes see random green, white, or blue flashes that almost appear to have ground, cloud or water textures on them, but they appear for just a fraction of a second, and sometimes Ill get multiple flashes in just a matter of about 10 seconds, but its mostly random and only when I move the camera viewpoint around land, not over ocean, though testing is also ongoing. Any help?