Category Browser with iPhone

Can anyone suggest why it takes so long to load the Category Browser (link in the right hand column on the home page) on my iPhone?

Using WiFi I typically get 10Mbps and a normal BC page loads in a few seconds. But the Category Browser typically takes 2.5 minutes.

The page appears in stages, with the authors taking most time - once they are complete the rest quickly follows.

On my laptop, also using WiFi, it loads in a few seconds.

So why the problem?