I'm having the same problem, not with GMail but with my university's mail. It sometimes takes up between 70-90% CPU, and at that time it doesn't appear when new mail is received. Ethereal does not tell me that it is making a lot of requests though. If I kill it and restart, usage goes back down to between 1-2% and the icon appears when new mail arrives. Network is connected, mail server is working. It is after a hibernate (although I can't be sure it doesn't happen before hibernate, as I'm almost always working post-hibernation).
I'm having the same problem, not with GMail but with my university's mail. It sometimes takes up between 70-90% CPU, and at that time it doesn't appear when new mail is received. Ethereal does not tell me that it is making a lot of requests though. If I kill it and restart, usage goes back down to between 1-2% and the icon appears when new mail arrives. Network is connected, mail server is working. It is after a hibernate (although I can't be sure it doesn't happen before hibernate, as I'm almost always working post-hibernation).