
I made some map with several reflecting solids and it worked fine

Anyway - enable the reflection so objects within 100 meters around, or whatever will be suitable and you are good

Or just mark the map *requires twice as good PC as other maps*

And yea - you can set up the level of details in reflections. On Crymod there was a nice post about mirrors somewhere, with images of reflective surfaces giving various details - like the blurred reflection for example of low-level one (that'd be fair good enough - even better than limiting reflections range to some very low value - still obviously it's best to combine both).
Also note that not all buildings needs to be a wall of glass

Just a few with some strategical meaning, where I could actually use the reflection.