I still don't really get the "feature". Is it that disabled fixed frame rate will more naturally playback the GIF as in: when I record a stopwatch it will show the proper timestamps? Imagine you start the recording exactly as when the stopwatch starts:
frame 1: 100ms delay are really 100ms on the stopwatch
frame 2: 122ms delay are really 222ms on the stopwatch
compared to fixed rate:
frame 1: 100ms delay are really 100ms on the stopwatch
frame 2: 100ms delay are really 222ms on the stopwatch
frame 1: 100ms delay are really 100ms on the stopwatch
frame 2: 122ms delay are really 222ms on the stopwatch
compared to fixed rate:
frame 1: 100ms delay are really 100ms on the stopwatch
frame 2: 100ms delay are really 222ms on the stopwatch