Yes: New launcher (1.0.51) causing stutter on Windows systems [SOLVED] - #49 by Dave_ZPCMR
It’s happening now because your frame rates are higher than before.
I’d also recommend removing/undoing all the tweaks and changes you’ve made, because the chances are you’ve made things worse. The problem is the Zwift launcher/installer (or more accurately, some files it installs); and using the workaround above resolves it.