HLS performance improvements

[ismena]

We can improve performance of our HLS implementation by

• reducing startup latency (such as fetching HLS segments to extract timestamps)
• improving bandwidth usage (such as polling all HLS playlists vs just one)
• possibly identifying other areas of inefficient performance

[michellezhuogg]

#1936

[joeyparrish]

We can improve performance of our HLS implementation by

• reducing startup latency (such as fetching HLS segments to extract timestamps)

This will be solved when #2337 is solved.

• improving bandwidth usage (such as polling all HLS playlists vs just one)

This is tracked in #1936.

• possibly identifying other areas of inefficient performance

I'm going to close this issue as redundant.