CPU overload msg at 17% usage

[MBseva]

Late 2013 iMac
Mojave 10.14.5
3.5 ghz Intel core i7 (4 cores)
32 gb RAM
internal SSD where ProTools lives
external SSD record drive
subscriber to latest PT 2019
At home user, CD projects every 2-3 years

I am starting a new project, vocals and acoustic guitars. I get persistent CPU overload messages on playback. I have just checked my most-layered song, with 20 audio tracks and a solid handful of plugins. 17% at peak!!

I do not understand what the problem is.

I have gone down the optimization list and done most of it. Thoughts....?

[BScout]

You haven't mentioned your audio interface or playback buffer (or sample rate). Those are the important details.

[MBseva]

Thank you, of course!

Focuserite Clarett pre interface
24 bit/44.1
256 buffer (have fiddled with this, makes no diff)

[MBseva]

I am attempting to upload a screenshot, but don't see it yet: basically, a shot during playback, with total CPU load at 16%, memory at 37% or so. I don't know what the "overload" is.

I should mention, my Focusrite interface is a thunderbolt unit.

[Southsidemusic]

Well ”gone down the list and done Most of it” isn’t good enough! You need to do EVERYTHING on the optimization list. Especially when you have these weird error messages.

[Rich Breen]

You have a lot of troubleshooting to do, since something's clearly wrong there, but obvious suspects are:
A wayward plug (try running session without plugs)
Some background process not related to Pro Tools (keep activity monitor open and sorted by CPU usage) - seen issues like this when people have software like Cleanmymac or AV scanners running in the background.
Drive problem (try session on another drive and suspect drive *off* the system)
Interface issue (is the interface connected thru a hub or directly to the machine?)
On and on...

[MBseva]

Rich, thank you! That’s helpful and I will check those items. As an intermittent user, I do appreciate pro advice born of long experience. Perhaps some day there will be error warnings that point to the actual source of trouble.

I have successfully recorded several projects over the last decade, always with a couple years in between. So when I set things up the way they worked last time, it’s a disconnect to be caught short like this, with mystery problems masked by ‘CPU overload’ that isn’t.

Mary

[MBseva]

Well, dang. My Focusrite Clarett 4Pre is a Thunderbolt interface, plugged into an OWC Thunderbolt hub, plugged into my iMac. Somehow I thought Thunderbolt/Thunderbolt would not be problematic. My iMac's 2 TB slots are taken up with the TB hub and TB SSD drive onto which I record.

Is that a likely suspect...?

I spose I shall have to plug direct to find out, sure. Just wondering if others have had that experience.

[Southsidemusic]

Just pull out a hard drive from a Thunderbolt port and put that in the hub so you free up a direct input for the Focusrite to try out.

[MBseva]

Already done. Turns out, one of my TB ports was in use by second monitor, which is now doing just fine thru the hub, while Focusrite is now direct. So far, so good! That might have been the ticket. Thanks again to Rich for the reminders.