Here we go... these were lifted from a forum post on the Reaper Forum
https://forums.cockos.com/showthread.php?t=288791 (see post #35)
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Reaper Preferences->Buffering
--Audio reading/processing thread = 16 (or sometimes 8 better) (14900K has 8 performance cores and 16 efficiency cores, hyperthreading gives you 16 virtual performance cores).
--Thread Priority = Time Critical
--Behavior = 15 Very aggressive
--Anticipative FX processing = on, render ahead = 200ms
----Allow on tracks with FX = on [I think is this is a typo : *without* FX?]]
----Allow live FX on 8 CPUs
Reaper Preferences->General->Advanced UI/system tweaks
--Do not allow OS to relocate worker thread = on (helps on some projects).
Process Lasso settings
--ProBalance Disabled
--Performance Mode Enabled
--For Reaper.exe
CPU priority = Realtime
I/O priority = High
CPU affinity = 0-31
Power Profile = High Performance
Efficiency Mode = off
Induce Performance Mode = on
Memory Priority = Normal
--For process svchost.exe (Local ServiceNetworkRestricted -p) [Audiosrv]
CPU Priority = Realtime
CPU Affinity = CPU 4
I/O Priority = high
Efficiency Mode = off
--For process svchost.exe (Local ServiceNetworkRestricted -p -s AudioEndPointBuilder) AudioEngine
CPU Priority = High
CPU Affinity = CPU 2
I/O Priority = high
Efficiency Mode = off
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