so when i load in lets say a 5 player server it goes to 20 to 10 fps then back to 60. in single player my fps is 80 to 100 idk why this is happening.
BeamNG and BeamMP is CPU demanding in most time. (i) Maybe your single or multi core performance is not keeping up with the game. (ii) Or maybe these spikes are just the events queue being updated.
For the case (i), try enabling simplified vehicles on Multiplayer settings. Also, in the Graphics Settings, you can lower or disable Shadows or Lightning effects, since most uses CPU and not GPU.
For the case (ii), try messing up with the Event Queue options on Multiplayer settings. I recommend update time to 10 seconds and speed limit of 7.2 km/h or more. Then you can play without lag spikes. When you see somebody with orange ball, you just stop and click on event queue (bar in the top of the screen). Everything will freeze for a moment and update.
No more driving excuses xD.
If nothing I told fixed the problem, please give more information about your hardware and how the computer behaves with low Graphics settings.
Cheers. See ya.