Do you think adding many MODS to the community folder will eventually slow the sim down? I am thinking that after lets say, adding 20 or 30 airplanes, then 100’s of new scenery directories, how slow will the sim be. I assume it has to read what is in there.

Loading yes, no doubts and confirmed by ASOBO. Performance, it will depend the quality of MOD, for example for cities. Bu t in general no.