Random denormals with P+E cores? (SOLVED)

[AtmanActive]

BUG: Random DENORMALS with P+E cores?

This is about VST plugins on windows and DENORMALS.

For those not familiar, DENORMALS happen when a plug-in goes into overdrive CPU usage when absolute zero signal is fed into it. As soon as there is some signal coming into the plugin, DENORMALS is gone and everything works correctly and plugin CPU usage is back down to 0.1%.

Now, recently I upgraded my CPU to 12th gen Intel i9-12900T which has some cores of P (performance) designation and some cores of E (efficiency) designation. I have no idea if this is related to the bug I'm experiencing but it could very well be.

I have VST plug-ins I have been using for years and for which I am absolutely sure they don't exhibit DENORMALS problem.
But, recently, I have random DENORMALS problem on random plug-ins, including the ones I was absolutely sure are clean.
Interesting fact is that DENORMALS problem doesn't happen when I use only one plug-in instance in the project, but only when I apply several instances on several tracks.

The other day I experienced this same DENORMALS problem with UAD Little Labs Voice Of God Bass Resonance. Again, I had the plug-in on a track for several weeks, working flawlessly. But, as soon as I copied it to several other tracks, those new tracks started behaving like DENORMALS problem, meaning, hogging the CPU abnormally until I press play or until there is some audio signal passing through.
This made me thinking that there is something going on in Reaper.
Since UAD plug-ins are not calculated in my CPU but in a dedicated DSP processor, there is, I believe, no way they are capable of introducing DENORMALS problems in my project.

Before you ask, yes, I did try to disable/enable "Reduce denormalization from plug-ins (recommended)" in Preferences->Plug-ins->Compatibility - no change whatsoever.

This whole experience made me believe that there is some other bug going on in Reaper, one that behaves like DENORMALS but it's actually not DENORMALS, and definitely started happening since I switched to i9-12900T (P-cores + E-cores).

And, just to make it clear: solution to DENORMALS problem is not "just press play" because the problems happen during the playback, when, for example, a track is gated and there is a pause in the audio. So, a project with this problem behaves erratically, playing normally, then going into buffer underruns (crackling), then again playing normally, and so on.

Also, in other words: as long as I'm putting only one instance of any plugin in my project, there is no DENORMALS problem observed. I mean, if a plug-in is broken, then it would exhibit this same behavior no matter what. But, it works perfectly fine until I add more instances and then, all of a sudden, starts behaving like DENORMALS problem.

Thanks.

[AtmanActive]

Reading release notes for v6.71rc1, I'm now convinced these problems are due to Reaper's auto-silent FX bypass feature in the making.

Not cool man, not cool.

Hopefully v6.71 will fix this.

[nofish]

If you only get this in pre-releases which contain the 'improve experimental silent-track CPU reduction option to include FX tail length' branch then you should probably post it in the 6.71rc1 thread so the devs see/may fix it before official release.

[AtmanActive]

Originally Posted by nofish

If you only get this in pre-releases which contain the auto-silent FX bypass feature then you should probably post it in the 6.71rc1 thread so the devs see/may fix it before official release.

The problem is I'm NOT on pre-release.
I was a few times on and off in past several months though.

[nofish]

Then I misread, sorry.

[AtmanActive]

Can confirm: this problem is gone since v6.71.
Reaper is back to rock solid.
Phew.
I was going crazy there for a while.