CEU x16 (HV) causes extreme performance issues (FPS drop from 60 to around 15). This only occurs when the player is within the same chunks as the CEU.

Might need more context, HV CEU by itself isn't the issue, at least not for me.

What batteries are in it? What's powering it? What's drawing from it? Are its buffers stable or fluctuating? Does it have unmitigated access to a power source in excess of 8192EU/t? What's next to it / in the same chunk / neighbouring chunks?

No Batteries, 6 Turbo Diesel Engines, Connected to the Main Power Line, so, everything is drawing from it?, Buffer was fluctuating i think, tried it in multiple chunks, even ones very far away from it

can't replicate