Performance question

[Apeirogon]

Not directly "How make X in Gzdoombuilder" question, but still...
I work on map where all thing, except walls and doors, is models. Lamps is models, light bulb if model, enemy is model, health pack is model, decorations is models, gl light is model, etc.
Now I starting create one big room, even BIG room but I though "If I put in this room as much decorations as in previous, plus enemy, plus fireball/projectile in fight time, plus gl lighting, plus hd texture, did it start lag to condition 'one frame in ten seconds'? "
So, is somewhere write how big room/how much actors I can put in one room to prevent lags? Or only run game after every ten-five placed actor to check framerate?