I have a Hisense 65" U8H that I bought about 3 months ago.
After reading the avsforum thread, I read that they advised to NOT use the native apps that come with the TV - like a CPU or cell phone - it can overload your TV and cause issues.
Everybody says - use a dedicated streaming player.
I use a Roku (which goes to my HDMI port #1) and I stream ESPN+, pretty much nightly, for hockey and I've had no issue.
I absolutely love ESPN+ as I pick the team feed I want and usually start from the beginning, fast forward to the 8-10min mark for the NHL action.
I'm about to chase action on PHI-DET in a few minutes.
The whole on-demand and fast forward and all the hockey makes it a dream app for me.
Easily my favourite thing to do since I got my Hisense.
But again - I watch solely thru my Roku and it has been absolutely fine for 3+ months now.
Last couple years I watched on another Roku going to our Samsung TV... that was also fine - though the app is MUCH better now for hockey coverage than it was last year.
Good luck. (sorry to hear your troubles - I think it's using the app through the native Hisense TV options... try not doing that. You may actually need a factory reset to clear out that clutter. Though - always sucks to have to get your credentials and passwords for all your apps set up with another device. But, try to avoid doing that... it may be bogging down your TVs ability to work for you).