Performance issues may be outside of Cloud CMS such as being related to firewalls or corporate proxies. One strategy for determining this is to run an ab test to gather timings from your computer to https://api.cloudcms.com or to the user interface server. This gives you a good approximation of where penalties are being paid and you'd expect to see ~70-100ms latency which we consider nominal.
Another thing to try is to run a connection test from the command line on the box that you're browsing from. You can do this using the latest Cloud CMS command line client, as described here:
Specifically, once you have the latest command line tool installed, you can do this:
cloudcms latency api
This will tell you the average latency between your box and the API. This can vary quite a lot depending on where you're connecting from. In the mainland USA, it should be around ~100 ms nominally but might be a bit higher. Less than 1 ms is actually spent within the Cloud CMS infrastructure - the rest is standard Amazon AWS latency through their network, load balancers, down to the ISP and into your corporate firewall.
You might also try:
cloudcms latency ui
This will tell you the average latency between your box and the user interface. This value can be different and may be a bit higher since it tests the SSL handshake as well. It may be around ~125 ms nominally. The same AWS factors apply.
If you're number are much higher then I expect the source of delay is outside of AWS and may be within your network. If they're close, then something else may be affecting the user interface speed - Please contact support with more information to help us to diagnose what that might be.