Switching speed doesn't render until synth queue exhausted

When the speed, rate, or voice is changed, the synth queue should be regenerated after the current segment is done being read (i.e. the rest of the queue after the current segment should be re-rendered)

Start by tracing the speed, rate, and voice controls to the synth queue and identify where the current segment and remaining queue are handled. The issue is done when changing any of those settings preserves the current segment and regenerates the rest of the queue immediately after it finishes.

Written by the indexing model from the issue text.