We had a high server load today, about 2 hours, that caused updates to run very long. We've done some fixes and everything looks fine now.
One thing to note is that when members are updating their site manually (ie. clicking the [Update Products and Settings] button), those requests are attempted to be handled immediately. It seems today many users were updating their sites manually many times and around the same time.
Automatic updates to your store (which run every X number of days) get queued and run one after another, not at the same time and therefore create much less load on the server.
Please consider waiting for your automatic update to run versus clicking the [Update Products and Settings] button every time you add a new product to a page. Also, keep an eye on your CHECKLIST. It will indicate whether you need to do a full update or whether a Settings Only update will suffice. Clicking the [Update Settings Only] button is a LOT less server intensive!