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. ■■■ 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.