I have been struggling with really horrible latency when browsing the internet from our office in Portland. I had thought that it was an issue with Firefox on OSX, but on further investigation the issues seemed to be related to DNS lookups. to fix this issue I have manually configured my laptop to use the OpenDNS DNS servers. So far the improvement has been very significant indeed. My initial observations would suggest that the latency is about a quarter of the previous automatically assigned Qwest DNS servers.
If you are seeing high latency, it may well be worth checking OpenDNS out. Its a well designed site with easy to follow instructions that offers a lot more features than jsut DNS lookups. you can configure your own URL shortcuts. so that for example you can simply type mail into the address bar of your browser and have it redirect to mail.google.com.