Seems like the audio sound channel manager is crashing and passing invalid parameters once this happens the game will run gradually decrease in fps til you leave match/rejoin.
C:\build\output\unity\unity\Modules\Audio\Public\sound\SoundChannel.cpp(214) : Error executing m_FMODChannel->set3DSpread(spread) (An invalid parameter was passed to this function. )
C:\build\output\unity\unity\Modules\Audio\Public\AudioSource.cpp(986) : Error executing channel.set3DSpread(cache.spread) (An invalid parameter was passed to this function. )
Attempt to set pitch to infinite value from script ignored!
NullReferenceException: Object reference not set to an instance of an object
at LevelInfo.GetAirDensity (System.Single altitude) [0x0003a] in <b180a3c4f72a4af8abfe6a9ef2c57c63>:0
at Aircraft.FixedUpdate () [0x0009a] in <b180a3c4f72a4af8abfe6a9ef2c57c63>:0
NullReferenceException: Object reference not set to an instance of an object
at LevelInfo.GetAirDensity (System.Single altitude) [0x0003a] in <b180a3c4f72a4af8abfe6a9ef2c57c63>:0
at Aircraft.FixedUpdate () [0x0009a] in <b180a3c4f72a4af8abfe6a9ef2c57c63>:0
NullReferenceException: Object reference not set to an instance of an object
at LevelInfo.GetAirDensity (System.Single altitude) [0x0003a] in <b180a3c4f72a4af8abfe6a9ef2c57c63>:0
at Aircraft.FixedUpdate () [0x0009a] in <b180a3c4f72a4af8abfe6a9ef2c57c63>:0
NullReferenceException: Object reference not set to an instance of an object
at LevelInfo.GetAirDensity (System.Single altitude) [0x0003a] in <b180a3c4f72a4af8abfe6a9ef2c57c63>:0
at Aircraft.FixedUpdate () [0x0009a] in <b180a3c4f72a4af8abfe6a9ef2c57c63>:0
NullReferenceException: Object reference not set to an instance of an object
at LevelInfo.GetAirDensity (System.Single altitude) [0x0003a] in <b180a3c4f72a4af8abfe6a9ef2c57c63>:0
at Aircraft.FixedUpdate () [0x0009a] in <b180a3c4f72a4af8abfe6a9ef2c57c63>:0
NullReferenceException: Object reference not set to an instance of an object
at LevelInfo.GetAirDensity (System.Single altitude) [0x0003a] in <b180a3c4f72a4af8abfe6a9ef2c57c63>:0
at Aircraft.FixedUpdate () [0x0009a] in <b180a3c4f72a4af8abfe6a9ef2c57c63>:0
Attempt to set pitch to infinite value from script ignored!
Attached is the player.log, 500,000 lines of it having NullReferences (i stayed in the game for 4-5 minutes at 2 fps trying to fly)