I think that MTA team should seriously consider reworking their stream-engine before adding additional so called "fancy" things. I can play every new game on a decent FPS, but I cannot play MTA with a stable FPS. Well, I can play alone, but with someone else around or on a race map built of objects, my FPS starts to swing madly. In full race servers (32 playes), the fps is just intolerable on map starts (goes below 20 with my rather modern hardware).
And I wouldn't blame faulty San Andreas' engine, which of course has a significant role in it as well, but when I used to play the crappier MP mod (SAMP) some years ago, I had no problems being in a same airport with around 100 players-vehicles. It had it's own faults (plenty of them, like quite small number of objects caused some lag already), but at least my FPS was more stable. (Not that I would like to play it ever again, just would like MTA to be more stable)
And to be honest, even in 1.0.2, my FPS was far more stable than it is now, and it's not just me, who has noticed this. When Asynchronous Loading was introduced, my FPS wasn't so stable anymore, don't know if it's directly connected to that, but I remember that from this time, I started having bigger problems and for many, MTA started stalling for seconds until they changed AsynchronousLoading settings from the menu. (From auto to on iirc)