Shaders precompiling
Shaders precompiling/precompiled shaders are something that's very common in games and emulators, it helps to minimize stutters...etc. For OpenMW itself this would probably be useful depending on the hardware, the idea though is this wouldn't just be useful for the original OpenMW shaders; but also modded core shaders.
As for an example in the OpenMW case, GL4ES had a precompiled shader archive feature for FFP and that alone helped alot with stutters for that case (using FFP).
When talking about this in the OpenMW discord server, AnyOldName3 had those thoughts:
"Theoretically we could note down which combinations of pre-processor defines were used and use them to pre-compile shaders on the next launch, which would reduce stutter, and if we wanted to get really fancy, also ship SPIR-V bytecode, but our shaders aren't so complicated that they take ages to compile, so they're probably not a serious cause of stutter."
https://discord.com/channels/260439894298460160/260443767482482688/1094268681862787172