TV portal slow & unreliable

Just got a 2000t and picked up this section on DS when I got the 'network not connected' message when trying the TV portal at set up.
I got it working after turning the box off & on again, but have found the service to be incredibly slow and half the apps don't work. I bought the Humax wi-fi dongle to connect into our fibre optic broadband. Co-incidentally I also just bought a new LG TV and the smart services work as expected - they load fairly quickly and work as they should (although, noticing some of the other threads, the YouTube app on the LG also has the odd video it cannot play).
Iplayer takes a long time to load and I've not been able to play anything on it for any length of time before buffering starts. YouTube doesn't load at all and have been put off trying any others (although the wiki tv works ok). Is this usual? It may just be my set up and I could try lashing an ethernet cable into it - but I may not bother if the TV portal is like this anyway. I know I can use my TV's smart services but I like eveything to work correctly, plus I shelled out £25 for the wi-fi dongle for this very purpose.