Edit: December 16th, 11AM, we performed the upgrade. There was a brief downtime of around 10-60 minutes, but everything should be fixed now! Timeout problems and the site going slow should be a thing of the past (or as a result of your ISP and not us for a change). Hooray!
We've been aware of the "Timeout" or "404" problems encountered when trying to access the site (or Designs not saving, for example) and we've been researching and coming up with dead ends over and over again. We ruled out hardware, software, and human elements, leaving... magic???
Obviously not the case.
Turned out it was a problem moreso in communication on the human side. Technology can be a tricky thing, and when we say one thing it's hard for the guys on the hardware end to account for every little detail. As a result, thanks to a variety of factors, the site had been capped for concurrent users at about half of what we needed. Something we should have caught earlier; so sorry about that.
So the good news is, we know what the problem is, and we know how to fix it!
The bad news is, turning up the variables involved will overtax the hardware, and we need to make another server upgrade. During the server upgrade there may be an outage of service, so I hope this is enough lead time for you. We hope to do the upgrade during the off-hours, so in the wee hours of the morning (Pacific Time) is likely. I'll try to update this thread when I have a more exact time, so you don't lose your contraptions.
In the meantime, we have maxed out the server as best we can. Refused connections should happen half as often - with the drawback that sometimes saving or loading can take 1-3 minutes sometimes. If you see blue bubbles or if saving isn't working, please! Go grab a glass of water and come back - it'll probably go.
Thanks for your patience in all this,