Here’s what I did to fix the slow as molasses on my mac:
1. Went into the configuration on my Linksys WAP/Router and put in some static DNS servers - using Google’s Free DNS... and 3rd entry my ISP’s DNS.
2. Flushed the DNS cache on my MacBook Pro: http://www.mactricksandtips.com/2009/01/clearing-your-dns-cache.html
Working like a charm now.
I just checked my Mac laptop. Problem has corrected itself without my lifting a finger. Strange.