Goes from 80-90 FPS taxing to 2-5 FPS/stutter fest EVERY TIME after hitting ~60 knots during take off sequence

but then it’s important to mention where the issues happen : 2D or VR ? ( note: for VR is own category ).

In case you can exclude issues caused from your settings ( e.g. to high load ), then may be there is some connection relevant stuff. We had some reports in case some kind of VPN is used.

UPDATE: found this topic, which sounds a bit like your issue: