This relates to desktop Windows PCs with an Intel CPU and discrete Nvidia graphics card. I can’t comment on crashing, other platforms or anything else that may also be going on. I’m putting this here because it’s clearly not being noticed in the game update threads, of which I’ve posted in two.
Zwift has always been CPU bound when there are a lot of other riders around; the frame rate tanks, with the GPU not being fully utilised. This is an unfortunate but fundamental and expected feature of how Zwift works and I’m doubtful we’ll ever get away from it. It happens to everyone, with how far the frame rate drops being dependent on how fast/strong the CPU is. When it’s not busy though, even very slow/old CPUs have always been fine for 60fps or more (the exception being Makuri Islands). In almost all solo rides, the game allowed the GPU to max out if necessary. However in the last two updates this basic behaviour has changed. I can only just max out a GTX 1050 Ti in perfect conditions (4K with vsync disabled, offline and zoomed in overhead); because otherwise the CPU is holding it back.
Until Jan 2022
Solo rides: GPU bound
Busy areas/group rides/Pace Partners: CPU bound
Makuri Islands: Mostly CPU bound even with nobody else around (for no apparent reason)
Since Jan 2022
All rides, all worlds, irrespective of rider density: CPU bound
I’m raising this because it’s a clear and obviously detrimental change to how Zwift behaves as a piece of software. It’s ruining the experience on systems that have previously always been capable of providing a rock solid 60fps unless the number of other riders nearby is high or the GPU cannot give any more. Some areas are very noticeably hit, such as the main straight on Richmond where simply changing the camera angle can invoke/revoke a massive performance penalty. I’ve observed this penalty being almost 30% on my main Zwift PC (170fps to 120fps). That’s bad enough, but on a budget system with lower end CPU you go from a reliable and constant 60fps to well below it. In that same spot on Richmond I was getting 47fps. Merely looking towards Titans Grove can see the frame rate drop hugely (75fps to 58fps) even when you can’t physically see it. The GPU isn’t rendering stuff you can’t see, but it feels like the CPU is still calculating for them. I’m sure some people will claim these frame rates are fine (below 60fps is… not okay) but my point is that this is massively inferior to how it was before, and how it’s been for literally years and years. All the time I’ve been aware of the platform at least.
If I had to guess, I would say that changes appear to have been made to how far into the distance the client ‘sees’ in terms of things it needs to compute on the CPU. The camera pointing down a long, busy road, or over towards an area full of assets/shadows, seems to be causing a massive amount of extra CPU load that wasn’t there before. Or maybe it used to be based on a proximity circle around the camera, and now it’s a cone going off into the distance and so it changes based on where you’re looking. Either way, the GPU is very often choked and the frame rate is lower than expected, like you’re in a group ride even when you’re not.
I really hope this is a bug or error that can be addressed as soon as possible. However if it’s a choice - say the rest of the game has been brought into line with Makuri Islands - then it seriously needs a rethink because it’s really damaging the experience for PC users and making the hardware requirements incredibly high compared to ever before.
Happy to provide log files and any other details that may help. Thanks.
