It seems like the site has been overloaded all day. Half of the time you get “This website is under heavy load (queue full). We’re sorry, too many people are accessing this website at the same time. We’re working on this problem. Please try again later.”
Of course, this makes it impossible to actually examine segments on activities or the city view.
Donate money to fund more servers!
It’s certainly possible that the problem is not enough servers, but given the sudden onset (~2d ago), something else may be going on. It’s also possible that the site is structured in a way that throwing more servers at it doesn’t make it any faster.
This thread is quite old, but I just recently found it in another category 
I feel like I’ve made a fair amount of progress on this particular issue, but I have more work ahead of me still. I think the biggest issue is keeping up with synchronization.
If I’m wrong about the “This website is under heavy load (queue full).” issue not being (at least mostly) resolved, please correct me. It’s so painful to realize a problem exists that I wasn’t aware of. 
I do think that the underlying site architecture allows for further growth. There are definitely improvements/optimizations to be made in order to reach 10k, 100k, etc members, but I think that’s to be expected - the things that work at 1k members won’t necessarily work at 10k.
That said, funding is a large part of the problem. I do need to be reaching my monthly contribution goals in order to scale out my infrastructure beyond where it is now. I really want to keep this site free to use, with added benefits for monthly contributions, and I feel like I’m finally starting to make progress in that area.