Have a look at this link for troubleshooting if you haven't done so already.
Otherwise set the ox back to factory settings.
I ran up a Now Stick yesterday for the first time in ages, fully updated it, and was gobsmacked at how slowly it displayed all 28 rows of the Home Screen.
We have 300 Mbps FTTP, so it wasn’t that.
I guess modern devices now outrun the older Now kit, and the Smart box precedes the Stick.
But do let us know if @gavs82008 suggestions give you a boost (small ‘b’), and I’ll try them myself.
Moving on, I thought I would try the Troubleshooting Step 4, linked to above:-
Changing the amount of ‘bits’ of data (the techie term is bitrate) streaming through your NOW Box or Smart Stick could improve your picture quality.
Fast Forward x2
You'll see a screen with various bitrate options. Just select Automatic and try watching your programme again.
But I don’t see such a screen at all 😢
I thought I might be doing it wrong, but the closely similar access to the hidden System menu by sequentially pressing keys
works perfectly, so I don’t think it’s that.
Any clues, anyone?