Zwift intermittent freezes

This is getting pretty frustrating. On almost every ride after half an hour or so, I get these intermittent freezes, where the game gets stuck for a few seconds, a handful of times in succession. Sometimes riders disappear, and only the bikes remain. If the freezes are short and not very numerous, I don’t seem to lose position, but many times I get dropped. On easy rides, I can recover, but if I’m working hard it’s “byby” peloton. I’ve given up on races because of this.

I’m running zwift on a second monitor (a TV set). I’ve gone thru the usual diagnostics to no avail.

Zwiftalizer output from my last ride attached.

The 2 fps extreme drops both sides of 7:20 correspond to the moments I had the freezes on this ride.

Nothing else was running on the laptop, apart from the usual windows junk. After the freezes I started the task manager (ctrl shift esc) to see if I could spot what was going on. Everytime I do this, Zwift window minimizes. Clicking on zwift icon again recovers the screen but on my laptop display, which requires a few keystrokes to to get the zwift window back on the tv set. For some reason the FPS reduces substantially after this. God knows why.

On the task manager everything seems normal. GPU @ 40%, CPU 15%, 300KB/s net, light load on disk and RAM.
I use Ant-FC and have disabled ANT+ on the tacx. I use an ant+ HR strap and a Garmin ANT USB pen. I have a wired 200MB/s fiber optic internet connection, with single digit ms latency.

None of this happens on other platforms (RGT or Rouvy).

I’ll be grateful for suggestions and help.

Luis