WebOS LG TV owner, and TouchPad owner here.
As far as I can tell, there's nothing obviously connected to the UI experience of the TV and the TouchPad.
The TV is a lot more locked down and filled with ads, but still snappy. Sideloading IPK's is limited. I would love to neuter all the ads and auto-updates, that's my main gripe.
My observation, after using LG TVs at countless hotels (occasionally internet-connected), AirBnBs (usually internet connected) and at home (never internet-connected) is that even in quite old TVs the UI is blazing fast until you connect it to the 'Net. At that point... It spends a painful amount of time waiting on requests with no visible feedback and the whole UI starts to chug, with some apps becoming almost unusable until the thing has been on for long enough for all the background stuff to finish.
Granted... If they aren't 'Net-connected, most "apps" aren't of much use. But, fast access to settings and inputs is sorta nice too.
> but still snappy
It's about the least snappy thing I've ever used, apart from cheap Android tablets (we made the mistake of buying an Amazon Fire Kids tablet which is the only device I've ever used that was literally unusably slow).
I even bought the higher spec version of the TV because apparently the cheaper version is even slower. Great image quality but I'll definitely never buy another LG TV again.
I have no explanation of what's going on with your touchpad. They really only had one model with different storage options. I guess I'd speculate there's something wrong with it.
As far as the TV, here's my model number:
OLED77C2AUA
No complaints about performance ever from me or my wife. Just the ads and software/features I don't care about. (No I do not want to update... Stop asking, I have auto-update disabled for a reason)
I don't remember the touchpad performance being all that bad for the time. Was pretty snappy IIRC.
My LG TV, on the other hand, definitely struggles particularly running apps. That might just be due to the age of the tv.