Well since I last wrote about this I have had more time to test, the outcome of which is that the Pi’s CPU still runs very hot even with the lid removed off the top of the case. This undoubtedly continues to be relevant to display performance which generally is still challenging. I have also found that Firefox ESR tends to crash quite often. Chromium is more reliable but unable to share the Firefox profile.
It looks like a $20 case from PBTech that has a heatsink to go on top of the chip, and a fan to pull air through the case, will be a necessary enhancement to ensure the chip is able to give its best performance. Right now, it runs quite poorly with videos, but does well when just playing music. With the current COVID-19 lockdown, I won’t be able to buy a case for quite a while yet, so I will just have to wait until an opportune time to get this implemented.