This has now changed to me being unable to load the game after logging in at all. I load the page, get the start screen, choose login, get the patch notes, log in, and it freezes at Loading Assets 0/1 with nothing in the progress bar. The Javascript console is filled with messages like this:
warning: 70 FS.syncfs operations in flight at once, probably just doing extra work
warning: 71 FS.syncfs operations in flight at once, probably just doing extra work
warning: 72 FS.syncfs operations in flight at once, probably just doing extra work
warning: 71 FS.syncfs operations in flight at once, probably just doing extra work
warning: 72 FS.syncfs operations in flight at once, probably just doing extra work
warning: 72 FS.syncfs operations in flight at once, probably just doing extra work
warning: 73 FS.syncfs operations in flight at once, probably just doing extra work
It started at 2 and over a couple minutes was past 80. Note it does not always increase, but never seems to decrease for more than a couple seconds.