Been trying to track this down as it's affecting all users. I can reproduce it usually by going through a few Opportunities, and editing the info in them (i.e. assigning to a sales person) or by sending a reply message within that Opportunity.
It will then grey the screen and say "loading" which then becomes "still loading" - usually takes 15 seconds then frees up.
I have restarted the Odoo server and the server itself without any change in the problem.
Looking at the log when this happens reveals nothing interesting, although there's usually a few INFO level messages about longpolling and email related tasks (deleting email is a common one). CPU usage seems fine when this happens as well.
Where could I start with this?