Firefox now gives Windows hints to appropriately set content process priority levels, meaning more processor time spent on the tasks you're actively working on, and less processor time spent on things in the background (with the exception of video and audio playback).

To improve battery life on dual-graphics-card macOS machines, Firefox now tries more aggressively to switch back to the more power-efficient GPU for WebGL content when able. Firefox also works harder to avoid switching to the high-power GPU for one-off transient uses of WebGL.

Finder on macOS now displays download progress for files while they’re being downloaded.