What exactly is your "convertible" in this case?
Also does it only lag for you in the Chrome Browser or do you encounter the issue as well when playing on the TV with the Chromecast or on mobile via Stadia app?
Regarding the graphics what you could try is setting the resolution in Stadia lower (e.g. from 4K to 1080).
Here are also some TS steps that I would recommend for you to try to improve your Stadia experience.
