I'm tearing my hair out on this one as well. It's a far more widespread issue than just Afrihost. Line stats are great, but having the same issues on Afrihost, Axxess, WA and Vox.
Some sites I visit frequently often load exceptionally slowly, don't finish loading, or don't load at all.
Sites like Youtube, MyBroadband, RARU, Loot, Takealot, Sharenet and quite a few others, are giving me constant intermittent loading issues.
I've ruled out my equipment by changing it out completely, tried alternative DNS servers, and even changed from ADSL2 to regular ADSL to see if that would work.
So far the only thing which completely "solves" the problem is using my 3G stick.
Speedtests and Tracerts all look perfect, so no faults to report.
My hands are tied, but it looks like I'm not alone in this. Lots of complaints, but nobody seems to know what's actually wrong.