Cache/Queue API calls
Currently if there are multiple API calls to the same URL with the same parameters, each call is completed individually and works as expected. This can happen if you have the same field on the page multiple times such as by design, or more often is the case, as an editable list field.
To make this more efficient I think it would be nice to generate a hash key for these API calls and cache them. We can then extend this cache to include a callback queue so that if there are multiple simultaneous calls (such as would happen with an editable list) only the first API call is made and the result is distributed to all registered callbacks.