Mir

Comment 0 for bug 1262116

Nested servers prevent full bypass from working. Or so I'm told at least... that we have buffer copies lingering in the nesting code that need to be eliminated.

This would explain why nesting fullscreen clients is measurably slower than non-nesting:
Direct (bypass) 2600
Direct (bypass off) 2400
Nested (bypass) 2450
Nested (bypass off) 2330