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net/audio optimizations (test)

Add this into your l4d2 steam launch options
-wavonly
-primarysound
-NoQueuedPacketThread (crashes when connecting to official servers,
not necessary for snd_mixahead 0)

NOTE:
with snd_mix_async 1 minimum value for snd_mixahead is 0.008
with snd_mix_async 0 minimum value for snd_mixahead is 0

snd_mix_async 1/snd_mixahead 0.008 seems to have less audio lag but not 100% sure.

Increasing net_minroutable may introduce stutters for ~1 minute when u first join/start the game depending on which gamemode you are playing.

On every 2nd server connect you have to set net_queued_packet_thread to 1 in main menu/in game menu (checked checkbox), otherwise the game will crash when connecting to server.
It will automatically change back to 0 after u connect.