You were right, and thank you — this report is what got it fixed. It was a real bug on Firefox: regular videos were mistakenly routed through a frame-capture path built for live streams, costing about half the frame rate plus extra CPU, and the buffer-trimming that caused the quality drops made it worse. Version 1.3.0 (just submitted to Mozilla, rolling out after review) fixes both: on the affected videos playback is back to the full native frame rate with the player left untouched. Your privacy point is addressed too — LagSync no longer requests access to all websites, only a fixed list of known video sites, with anything else strictly opt-in per site. I'd be grateful if you gave 1.3.0 a try.