Have you tried switching WIFI off on the MAC when in its usual position and wired to the BT Giga thingy?
If browsing is still slow,open Network Preferences and click on assist me and then diagnostics. Might give some clues.
I had a problem with my iMac and slow email and slow/delayed loading of web pages and it was due to my Netgear router being set to an old version of RIP. Once set to RIP-2M it all worked fine. I also had a switch and Time Capsule involved so it seems these needed RIP to work properly. Is there such a setting in any of your devices?
There are a few little apps that I've found useful over time. One is 'iStat Menu' which monitors the system so you can see what's happening with speeds as you're loading web pages and the other I have is 'Little Snitch' which was origionally meant to monitor outward traffic but works both ways. Both cost money but might give you a clue to the problem.
There is no setting that I am aware of. The only software visible to me on the BT Smart Hub is the firmware and that seems to update itself automatically. The last update was a few days ago.
Thanks. Yes, I have tried swiching WiFi off when the Mac is in its usual position. That doesn't seem to make any difference. I suspect the Mac goes for the Ethernet connection if that is available, even if WiFi is switched on. I have now tried using the diagnostics in Network Prerferences when only Ethernet is connected, but that just tells me everything is OK. (Download and upload spped using a broadband speed tester are OK, it is only web browsing where there is a clear problem.)
Wjen you browsing in Safari, rught click and select inspect element. This will bring up the info at hr bottom of the pag. Are there any warnings shown?