I've had a 9T for 2 months to the day, as it turns out.
There are some times when I (it) experience(s) lag, mainly in MX Player, just scrolling through the folder listing it's evident.
That app has become a bloated dog with all sorts of (unnecessary) features, in my view being added, so I'm unsurprised.
Also occasional lag in Brave browser if you let browsing data build up too much & don't clear it often enough.
Also, switching from portrait to landscape & vice versa isn't as smooth as I'd expect from a phone with 4 GB RAM.
Another thing to be aware of is "dead boot" which you can read countless accounts of in GSM Arena -
m.gsmarena.com
Seems to have affected phones sold in North Africa (Nigeria) and parts of Asia so far, but something to at least be aware of.
Otherwise, it's pretty good value for money, but I'm not blown away by it.