Best BeamNG mods that don't tank performance?

Get them from the in-game repository rather than random zip sites. Not everything there is great, but at least it loads and gets updated. The fps killer is usually maps, not cars. Big detailed terrain maps hammer VRAM, and a 3060 laptop runs out of that quickly. Cars only really cost you when they're spawned, since physics runs per vehicle, so turn the traffic count down before you blame a car mod. If a map drops you to 20, try it with traffic off and texture quality one notch lower. If it's still bad, it's just a heavy map.