load caching time is too long

When the video file is downloaded to half, I hope it can be played fast next time, but now it's too slow, how can I optimize it, my player is MediaPlayer, thank you.

Start by reproducing the reported case with MediaPlayer: download a video to roughly 50%, then retry playback and measure how long loading takes. Trace the cache and playback entry points involved in partial downloads; done means a partially cached video starts faster on the next attempt without breaking normal playback.

Written by the indexing model from the issue text.