Real Time CPU Bursts When Moving Mastser FX Chain to One of The Normal Track

[vicnest]

I wanted to do some more complex master chain.
So I decided to move Master FX into one of the normal track ("Everything Group"). But now the playback suffers hugely due to RT CPU keeps hitting over 100%. And there's no meter to see which channel use how much RT CPU.
In order to playback smoothly. I have to increase Anticipative FX Processing from 200 to 500 ms or 2000ms depends on how late stage I'm in a mix.


This situation happened to me once before in Reaper 6. I was sure why.
But this time right after I moved the chain to one normal folder track as "Everything Group"), the playback stutters.

I've done similar operations in Reaper 5 and don't remember suffer similar crazy RT CPU hit.

Track 3 is reference track with ADPTRMetricAB disabling Anticipative FX Processing (or else the very first sound stuttered).
Track 6 happened to be available as a group track containing everything (other group folders and tracks) else.
The RT CPU jumps from 15.7% to constantly over 100%.