Since yesterday's micro-patch 6.2.2a I'm seeing the game client frequently locks up for 5-15 seconds when viewing other characters' bank contents. The amount of time seems to be related to how many items are in the selected bank. It always happens the first time a particular bank is viewed in a login session, and sometimes when viewing the same bank again later.

For example, I'm on (Paladin) and I open the bank frame, then select (Shaman) in the menu. (Shaman) has all 30-slot bags in the bank. The bank frame resizes, and all the slots get an icon count displayed as needed, but only the first 1/4 or so of the icons are populated, and then the client locks up for 10-15 seconds. Windows offers to close the unresponsive program. Eventually it recovers and fills in the rest of the icons.

Now I select (Warlock) in the menu, and the same thing happens, though (Warlock) has slightly smaller bank bags, so the lockup is only 5-10 seconds. Windows only offers to close WoW if I click on it too much while it's frozen. Eventually it recovers and fills in the icons.

Now I select (Druid), but (Druid) is a low level alt with nothing in the bank, so there's no freeze.

Now if I select (Shaman) or (Warlock) again, it might display right away, or it might lock up the client again.

I've never had this problem before the patch, and it still happens when Bagnon is the only addon enabled, so it's not related to any other addon updates since the patch. No Lua errors are raised.

Edit: I should add that it doesn't happen when viewing the current character's cached bank contents, only other characters. Opening the bank window for the current character while not at the bank results in the same modest <1 second hiccup it always has.

Edit #2: Also happens when viewing other characters' non-bank bags.

Possibly related, while remotely viewing any bank (including the current character's bank) dragging the bank window around the screen is reeeeallly slow. FPS drops to single digits and the window lags far behind the cursor, then jumps into place, then lags again, etc. I'm pretty sure this started around the same time, so it's probably related, but I can open a separate ticket if you want.

can relate, experiencing the same

This also happens every time I open my own bank (without being at the bank) before having visited the actual bank in this session. Only noticed this since 7.0.