I don't think that FPS drop is related to meshes/LOD or the renderer at all. The renderer is pretty much the only good part of the engine (and still has its issues), everything else always has been sup-par compared to other game engines at the time.
I'd guess the renderer doesn't have much overdraw and can generally figure out what not to draw.
IMO, the most likely cause is the AI/Animation system, especially its reliance on Lua. And bad Lua code at that.
As mod-able as Lua makes STALKER it also makes it slow.
Running all those scripts in a single Lua instance just cannot scale.
"If debugging is the process of removing software bugs, then programming must be the process of putting them in." -- Edsger Dijkstra
What I'm trying to do, is to make a crossover of online and offline mode on an active level.
I added a parameter called ai_switch_distance and if an NPC is further away from the player than this distance, almost all action scripts and evaluators (apart form those basic ones like walkers and kampers) are shut down.
Still, I'm getting a big FPS drop.
But I'll take your word for it and try to deactivate things further.
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