What I've noticed is that these freeze problems are ultimately concern with how much you stress your GPU, I started working in that direction as I noticed that in Medium graphic settings I experience no freeze.
Even after upgrading my 970 GTX to 1080Ti (3 monitor setup) I still had lot's of freeze in 2.5 (and Normandy 2.2 beforehand) with High graphic settings.
But luckily I got to somehow minimize these freeze significantly this way:
* FPS limit: Limit to 45 FPS (Config/graphics.lua maxfps setting), though I might get up to 180fps without this setting in different scenarios, limiting it probably makes the GPU handle pick loads better
* Max FOV: Decreased max CameraViewAngleLimits for the relevant module to 140 (Config/View/Server.lua), greater FOV means the GPU has to render more of the surrounding virtual world
* NVidia Control Panel: as attached, note the bold ones
* DCS graphic settings: as attached, specifically higher values of Preload Radius and Clutter are very encouraging freeze, and I used NVisia's FXAA instead of in-game MSAA
and another one that doesn't hurt: after changing graphic settings - delete fxo and metashaders folders (under Saved Games)