The performance problems are caused not by the latest update to Premiere Pro, but instead by the latest update to the Creative Cloud desktop app. Adobe engineers tested several older Nvidia drivers, and found major issues with those older drivers across several Creative Cloud apps, which might have included Premiere Pro. So, rather than issuing compatibility error reports on an app-by-app basis, it decided to issue the compatibility warning globally across all apps. Specifically, for Premiere Pro, if you are running the newest update to the Creative Cloud desktop app, then you must also update the Nvidia driver to 451.77 or higher in order to work properly. If you ignore this compatibility warning, and continue with issues using the older drivers, then all hardware acceleration in Premiere Pro will be disabled with no indication or warning at all. And older versions of Premiere Pro will not even tell you that; the program will simply launch normally, but you will definitely notice the severe degradation in editing performance as these older versions will not even tell you that you're locked into software-only rendering and encoding unless the driver version is really, really old.
And the above applies to all currently available versions of Premiere Pro, not just the latest 14.3.2 version.