Gmail's iPhone/Android-optimised webapp is nearly as good as a mail client, but not if you keep multi-multi-message threads near the top of your queue. One blogger saw a nearly 7-second decrease in loading time after killing one seemingly endless chain.
The Just Another iPhone Blog saw his webapp refreshes crawl to an average of about 10 seconds from the 2-3 second norm he was used to over 3G service. The culprit? A really long email chain (40 messages) about various post drafts.
Once I archived that conversation my Gmail web app was back to being spry and reactive, with a renewed refresh rate of about two seconds. So I guess the moral of the story for heavy Gmail users is to clear your inbox of huge e-mails…or maybe just don't talk so bloody much under the same subject header. ;)
Sage advice in any email client, but very relevant for mobile users wondering why their speeds seem so different from day to day.
My iPhone Gmail web app was insanely slow – it turns out one convo was too big - [Just Another iPhone Blog]