Scrubbing Autoplay is not very good

[yuuiko]

Describe the bug:
Pretty sure this is just a placeholder for a more advanced system, but currently, scrubbing in a replay isn't very good. It just plays the beatmap at a high speed. It takes a long while to catch up to the scrubhead in a long song.

Screenshots or videos showing encountered issue:

osu!lazer version:
2019.616.0

[peppy]

tHis is limited by the actual performance of playing back the replay currently. It will improve over time until we can make it feel much better.