Google recently launched Chrome OS version 91.0.4472.147 update for Chromebook users. The update is now reported to be causing performance issues for some Chromebook users. The performance issues were first pointed out by users on Reddit and has since picked up some comments on the Chromium Bug Tracker. Users said that pretty much every website lags horribly, even after disabling extensions. The problem here seems to be that the Chrome OS version 91 seems to hurt performance by overworking the CPU. One users found that that CPU usage often hits up to 100 percent with the clock speed dropping to 0.80GHz - a fraction of the power available on most modern Chromebooks.
According to reports, the problems are immediately noticeable after you update that machine. However, not all devices seem to have been affected. According to a report in Android Police, most reports are from the “hatch" and “grunt" boards that come with 10th Gen Intel chips and some AMD chips as well. Those who have not updated their Chromebooks to version 91 are advised to hold off until Google has fixed or at least acknowledged these performance issues. If you are already affected by the performance drop, switching to the beta channel temporarily might help. Users can send feedback to Google by pressing ALT + Shift + “i" on their Chromebooks.
Some users also reported that even doing the basic things like typing, navigating around the UI, and opening apps seem to grind the PC to a halt. They said that performing the usual troubleshooting like disabling all extensions, performing powerwash, and restarting the PC isn’t helping either. We have reached out to Google for a response on the same and will update this space as and when a response is received.