* Loading GMail takes up to 20 seconds. That was only one time, but at least once a day I see "Loading <myemail>@gmail.com" for >5s.
* Sometimes conversations take seconds to load.
* I usually see "Sending..." for a few seconds when I send an email. Occasionally, I get server errors when sending.
* Searches are even slower than they've always been.
And I'm not even close to hitting my space limit: "You are currently using 708 MB (9%) of your 7515 MB."
Another issue: I have 4 Priority Inbox "sections": Important, Starred, a label, and Everything else. The sections with Starred and the label are often stale. Right now, the label section just has nothing in it. There's plenty of email from that label.
If anyone from Google is reading this, my email is in my profile, but not the one that's the problem. Email me, and I'll be happy to tell you my @gmail.com username that is problematic.
As an example of how slow Gmail is at times: I've started a search for something before going out to lunch for an hour. When I came back, it hadn't found any results yet. As far as I could tell, it didn't time out. This was sometime in July and it hasn't gotten any better.
There's also the problem where mail from my college's mail server shows up anywhere from 30 minutes to 3 days after it is sent out by someone. Needless to say, this causes problems when talking to professors, unless I use the email account provided my my college.
And this is in Chrome - not some kind of Google-forsaken browser like Opera.
* Sometimes the Inbox display count on the sidebar and the contents of the inbox get out of sync. E.g. The sidebar displays "Inbox (1)", but there are no unread conversations displayed in my inbox listing until I hit the 'refresh' link at the top of the inbox.
* Searches take ~10 seconds or more.
* Sometimes actions start to timeout with a "Loading...", which turns into a "Still Loading..." which sits there for 20 seconds or so before the action goes through.
* A couple of times the gchat applet has timed out while the rest of the gmail interface worked fine. A full page refresh didn't fix it (it would continue to timeout while trying to log me in). After a full page reload the GChat app completely disappeared. Even the 'enable/disable gchat' links at the bottom of the page were missing. Once I was able to remedy this by deleting all of my cookies for * .google.com. The second time I had to find a forum post suggesting that I enable the Google Labs feature to move GTalk to the right side of the Gmail interface (which worked). A week later I disabled that hack and the regular version was working again, though sometimes it will timeout.
* Sometimes co-workers will appear offline in GTalk even though they aren't.
* Sometimes a GTalk conversation will get into a 'wedged' state where it is impossible to close the little popup window (only minimize it). Neither hitting Esc, not clicking the close button/link with the mouse will get rid of it. The only remedy is a full page refresh (which is akin to just re-logging into Gmail; the 'loading' progress bar comes up and everything).
It's important to note that sometimes when things start to timeout, it will happen for a period of maybe 5 minutes or so, and then everything is snappy again (this applies only to the Gmail issues, not the GTalk/GChat issues). And during this time none of my co-workers is having any issues. But we all experience the periodic DoS of Gmail (for lack of a better term).
This is why I use a desktop client.
Global search is an evil POS.
Although I have noticed a little slowdown. Just noticing the higher standards for Google while I'm at it :)
[1] this happens equally in bad network reception conditions and excellent network conditions.
Opening email and opening the rich text interface when composing are the two places I see it most. Sometimes the operation won't complete at all, claiming there is a connectivity issue. Other times it will complete, but will frequently take 30+ seconds.
Search is consistently slow.
Displaying a message after clicking on it is sometimes very slow, sometimes ok.
Sending messages can take an inordinate amount of time on occasion.
Receiving email is still generally reasonably fast, but occasionally a message will take an hour to show up (messages before and after it showing up just fine).
Overall it feels quite sluggish, nothing like it was a year ago.
The new Yahoo Mail on the other hand is surprisingly fast and slick. Quite a role reversal.
Also, loading Gmail indeed takes about 20-25 seconds, but that's a small issue for me (yay for one-time costs).