Was there a patch uploaded recently for Steam versions?
I have noticed that in the last few weeks (i.e. August-September, 2016) my Arma 2 OA performance unexpectedly improved. Earlier there was an error displaying the ground textures in first person view, now it is gone and all details are nicely visible. Furthermore, the previously slow Armory section acts much quicker, e.g. targets appear faster on the screen. I asked Steam support but they did not reply yet.