It only happens with Maps and is reasonably easy to reproduce. For example, Kibana usually crashes if I open the same map in 3 different windows and reload them all. You don't get much additional information from developer tools. The xhr requests fail with a 504 error followed by a number of 502's.
The maps displays document layers with geo_shape fields. Here are a couple of screenshots to show the type of information
I'm not able to increase the memory on the Kibana instance. The control for doing this is greyed out. I suspect that is a limit for a trial account. How confident are you that increasing the memory will fix rather than shift the problem (e.g. from 2 to 10 concurrent users)?
I'm happy to share the data. Not sure how to do that. There are 1.3 million documents spread over 5 indexes.