When I first load into any game, I get perfect FPS, faster than I can see, and perfect mouse movement. This was accomplished only after making standard config changes (see below). My gear is below minimum specs.
I get consistent perfect performance out of DayZmod no matter the load on similar (but higher viewdistance) config. All config info appended below.
Anyway, in SA, my initial perfect FPS degrades over time, usually when running from place to place, but then again thats mostly what I do. Havn't extensively tested it, but standing still for a while appears to remedy. Can sometimes remedy for no appreciable reason. Appears to be worst in wooded areas. Least effect in cities.
By the way, if possible, send me an email if I have overdone my lowering of settings, such as things I can safely increase without degrading performance. Ive just hit everything as low as possible to try to solve my issue.
Also Send me an email or otherwise contact me if you need any further info concerning this report. I'm sure I've missed giving you some critical info needed to debug this issue. Please let me know.
Actually find it sort of funny that I perform amazing on the Arma2 Mod, no issues at all, when that is supposed to be even less optimized. I really hope this is fixable. Best of luck tracking down root issue. I will help however I can.