More of a PSA considering I’m unsure Zwift even read this forum any more.
I don’t know if the recently publicised new launcher for Windows installs additional telemetry or something, but on several PC builds I have confirmed it to be the source of newly observed stutter in the game irrespective of circumstances or outright performance/frame rate.
All Windows 10 20H2, fully updated
All Nvidia driver branch version 45x.xx
All on latest version of Zwift game, installed with launcher 1.0.51
All 8GB RAM
All running from SSD
All ethernet to 40Mbps broadband
All using full screen mode, as selected in the Zwift settings menu
System 1: GTX 1060 6GB to 1440p Gsync compatible monitor
System 2: GTX 1650 Super to 1440p Gsync compatible monitor
System 3: GTX 1050 Ti to 1080p 60Hz TV
On all systems, whether matching display refresh rate (TV/monitor) or below (Gsync monitor), the expected smooth motion was missing. Noticeable stutter was present at all times, in and outside of group events, when quiet and busy in terms of logged in numbers, on different worlds, and at different login times. Most easily seen by using camera view 9 overhead (the road beneath passing by very unevenly), watching other riders coming past in the opposite direction, and noting the motion of static objects passing by such as street lights etc.
Reinstalling the game from scratch with launcher 1.0.51 including clearing all files and rebooting made no difference.
Reinstalling the game from scratch using launcher 1.0.44 or 1.0.50 immediately restored the expected/normal smooth performance, without changing anything in Nvidia settings, Windows or display settings, or any other changes to the systems whatsoever.
Further testing shows that switching launchers as an in-place upgrade/downgrade (i.e. without full reinstall of the game) repeatedly introduces (1.0.51) and eliminates (1.0.50) the problem, so there’s something clearly not right with the current version. I’d therefore recommend Windows users stay on the previous launcher version rather than upgrading, for the best experience.