Recently i've acquired two TCL televisions with GoogleTV, a C825 for my living room and a C725 for my bedroom.
The C825 felt alright in the first few hours, but then it became a bit slower, sometimes the home page is laggy and unresponsive, and Disney+ works only when it feels like.
The C725 arrived yesterday and the GoogleTV on there feels considerably smoother to operate, even after hours of usage.
Perhaps i should reset the C825 and try again?
A reset wouldn't hurt... It's odd though seems like it should be the other way around. Your c825 has 4x A-73 cores max clock 1.6Ghz, and your c725 has 4x A-55 cores max 1.3Ghz.
The c825 could be throttling once it gets heated up perhaps? You could try putting a fan near an intake thats close to the soc