Spikes and overloads on C12 Pro when adding only 1 extra audio track

Hi, I struggle to have my Cubase Pro 12.0.60 working properly on my Mac with a reasonable project.
Everything is fine with the performance meter at 40%.
When I add a stereo audio track, then import a 4 bar audio file with musical mode enabled the computer gets crazy with spikes drop outs and in the end the infamous mac beach ball.
If I delete the audio track completely the problem remains even if it should come back working as before I added this new audio track. It makes no sense at all.

I read all the thread about asio guard problems but could not find any remedy in there.

Latency is at 1024 samples on a mac mini i7 2.3GHz with 16Gb of RAM.

I noticed also the CPU gets less load when arming for recording an instrument track.

Is it a common issue or just my setup going wrong?

I resigned to freeze all my def instrument tracks to gain some power but, there’s definitely something wrong.


Of course, because the ASIO-Guard does the job ahead, so the CPU is much more relaxed.

We had reports about poor performance in the last weeks, when it turns out that there was 3rd party software installed, that disturbed the general system performance. But it was mostly on Windows.

Could be a starting point.

The most confusing part is when I remove the audio clip and track that provokes the overload, cubase still stutters and drops out. it should come back to normal (40% power usage on the meters). It’s like the buffer or the memory is not freed from the extra load added before.