Newbie post - strange routing for ZA to UK via USA?

[Phlippie Smit]

Hi there

Could anyone please explain how routing to a website works?

I basically need to know what happens when a site is requested by a web
browser in one country, when the site is hosted in another.  For the sake of
the example, say the site is in the United Kingdom and the visitor is in
South Africa.

The way I currently understand it:

1.  My browser interrogates my IP settings and finds a DNS server.
2.  The DNS server "traverses" until it finds a DNS server with the
requested site name, and converst this to an IP address.
3.  My Computer connects to the other IP adddress.

The actual question (excuse the long intro):

Why do some sites first go through the USA and then only to the UK (Is it a
routing or a DNS problem)?

I have tested the following sites from South Africa:
www.pipex.net - goes directly to UK
www.yell.com - goes directly to UK
www.activitybreaks.com - goes the the USA and then to UK

Why do some sites have more and other less "hops" to the actual www server?

Would the strange route from South Africa to the UK slow down traffic to the 
site? (I have used NeoTrace to view the route and nodes in the path)

any help will be much appreciated.

TYIA

P Smit