However, it seems Apple didn’t entirely think through the implications. Most seriously, with All Mail enabled, Mail periodically gets into a state in which, according to the Activity panel (choose Window > Activity), it’s synchronizing my Gmail Archive (that is, All Mail) and updating the cache directory for my Gmail account. That’s all well and good as long as it happens in the background. But when one of these syncing fits starts, changes to messages in my Inbox made in other clients or on the Gmail Web site aren’t reflected in Mail. Not even if I quit and restart Mail, or rebuild the Inbox, or force a synchronization! There appears to be nothing I can do but wait, and sometimes that wait is hours. Worse yet, sometimes the syncing ends — Mail’s Activity panel shows zero activity — and still my Inbox is out of sync for a long time. (For example, as I write this, Gmail shows I have no unread messages in my Inbox, but Mail shows 10, including some I filed more than two hours ago.) It’s not like this happens all the time; sometimes Mail syncs up with Gmail instantly, as it should. But this is the behavior that makes me truly crazy — if I have to keep Gmail open in a Web browser to make sure I’m getting all my messages, I might as well not be running Mail at all.
I’ve started to notice this as well since i installed yesterday