I’ll have to give the Handbrake beta a look. I’ll report back.
EDIT: Using the universal binary beta with the VideoToolbox H265 encoder I am seeing ~64fps with a 1080p BD -> H265 (CQ 42)
EDIT: For fun, I wanted to see how it would do strictly on battery… encoding speed dropped a hair to 60fps, but the battery life estimate in battery monitor is roughly 6 hours from a full battery.