frameBudget property
How long a single drain pass may spend inside Terminal.write before yielding to let a frame be produced.
Measured against a 16.7ms frame: 8ms leaves room for the paint the write just dirtied. Going lower does not buy more frames - 4ms measured the same frame rate as 8ms and only drained more slowly - so treat this as a ceiling on stutter, not a tuning knob.
Implementation
final Duration frameBudget;