Each component that uses external_files (audio_file, speaker
media_player, ...) currently calls download_content once per file
inline inside a per-item config validator. With ~24 cached audio
files in a Home Assistant Voice PE config, that means ~24 sequential
HEAD round-trips, even when every response is a 304.
This adds download_content_many(items, ...) which fans the per-file
checks out across a ThreadPoolExecutor (capped at 16 workers so
configs with hundreds of files don't open hundreds of sockets), then
refactors audio_file and speaker.media_player to collect URLs at the
list level and call the batch helper once instead of downloading
inside each per-item validator.
Wall time for the validation phase drops from sum(latency) to roughly
max(latency) when the cache is warm.
J. Nick Koston
2d9d1eabfa