How can I turn off Screen Space Reflections for one or more materials? Because this drags down the framerate on UPBGE 0.35.
Since using Screen Space Reflections is already a technic to fake more complex calculations… meaning: needing less computing power… by using information in the geometry buffer… so more postprocessing than actual 3D data computation…
…i guess: your scene is a bit too much for your actual machine… 
This is more to do with UPBGE rather than my actual computer, as M1 can handle it perfectly. UPBGE needs more optimisation and work done on the Mac side before 60FPS with raytraced SSRs become a real thing. The Sims 3 ran perfectly well with reflections using an intel iMac, so the problem is definitely UPBGE.
Of course nobody could presage your actual computer specifications… and so the implementation level for this hardware… nor the complexity of your scene in contrast to any scene used in any other game engine…
(…and i also don’t know what technic exactly was used in Sims3…)
Back to you question: i’m not aware of any masking features for SSR to use it only on specific parts of the screen… only EEVEE parameters (in standard Blender) like:
- additional Refraction
- Halfres Trace
- Trace Precision
… - Clamp
to tweak the appearance and/or performance.
I recall in 0.2x that you could do realtime reflections via cubemap textures. Is it maybe possible to do this in 0.3+? I see no such node except for Environment Texture. Trying to do ImageMirror will not work on M1-based Mac computers as it doesn’t properly support GLSL, so that feature is out.