Zwift freezing for 10 -20s



During rides everything just stops for 10 -20s and when it returns I lose any progress made during the freeze.  I am running Windows 7 (64bit) with an Intel Core 2 Duo E8500 @ 3.16GHz with an AMD Radeon HD 6800 graphics card.

Zwiftalizer reports my ANT is up and down like a fiddlers elbow yet I have followed all the remedies suggested and have the dongle on a quality extension and placed 1ft from the Kickr.  While this would appear to be the cause I suspect that the PC / software is hanging and not reading the ANT signal. Is this possible, I would hate to be buying a new dongle if there is nothing wrong.


Hello Mike

This sounds like a computer issue not the ANT+ dongle.

It may be Zwift is pushing the limits of your PC’s performance.

Have you tried running Zwift at a lower resolution?

Zwift freezes occasionally on our PC as well. The freeze lasts a few seconds; I estimate less than ten. I don’t notice a freeze most rides. It’s enough to notice, but not enough to be a big issue here.

By freeze I mean that Zwift’s display on the PC becomes fixed for a few seconds. I’m pedaling on the trainer, but the avatar and watts and power and heart rate, etc., on the screen – the entire Zwift display – are stuck. Meanwhile, software on the second screen goes on functioning.

I don’t see this being a problem with the PC hardware. Both the cpu and the graphics card run Zwift smoothly (60 FPS) at 1080p ultra, without taxing the capabilities. And the freezes don’t seem to happen at especially complex moments. Yesterday I had a brief freeze when just a couple of other riders were in view.

I also don’t see it as an ANT+ issue. Otherwise, the Zwift display wouldn’t freeze. It would be as if I’d pulled the ANT+ dongle – 0 watts, 0 cadence, 0 heart rate – while I’d coast to a stop in Watopia and the riders behind me would pass me and the riders ahead would fade into the distance.

Likewise, it doesn’t look like an internet connectivity issue. If the internet disconnects, I keep going, just without seeing other riders.

Yes, in agreement with you Steve.

I have experienced this stop-go issue on an older PC. I put it down to other software running in the background taking resources. After a while I noticed the freeze seemed to be happening at the same place/location in a Zwift session, i.e. more often than not on entering the Mall in the London course. The introduction of spectators around that area made the issue more pronounced. To me, that suggested a program taking background resources was unlikely.

That older PC is running an i5 with 4GB and a mid-level Nvidia GT 705. at 1080p

I had cause to buy a new PC and all the momentary freezes went away.

The new PC is i7 with 32GB and GTX 1080. with 8GB. at 4K.

Thanks, yes that’s why I suspect the PC. Zwiftaliser says my max and average fps is good but isn’t happy with the minimum.  Currently setting up a spare PC to run it and nothing else to see if it eliminates the issue.  It has a meaty graphics card (Nvidea 8800 gt) so we’ll see.


Mike, I’ve had the same. It would freeze & when it caught up I was in same spot bit everything around has moved on. Great training as I had to sprint to get back into bunch.
It was categorically an issue with my PC. Ended up doing a full factory reset & it sorted it.