cache_pause=no caused frame-wait-frame-wait on uncached videos
because mpv kept playing through buffer underruns instead of
pausing to refill. Flip to cache_pause=yes with a 2s resume
threshold so playback is smooth after the initial buffer fill.
Also: bump demuxer buffers (50→150MiB forward, add 75MiB back for
backward seek without refetch), increase stream_buffer_size from
default 128KiB to 4MiB to reduce syscall overhead, extend network
timeout (10→30s) for slow CDNs, and set a browser-like user agent
to avoid 403s from boorus that block mpv's default UA.
behavior change