Bad Performance with large number of EDM Macros

Description

Customers have reported poor macro loading times, especially when used inside of Page Property Reports. The most common case seems to be that we encounter the performance issue when a large number of macro's are displayed on a single page (50 - 70, or more). If the amount of macro's are sufficient, macro's will load slowly and in drips and drabs.

Cause

Atlassian only allows 6 connections from the same origin at a time, hence leading to the stalled requests. Each individual iframe (which our macros are in) creates a connection and request, and subsequently stalls until resources become available.

We already made our macro's cacheable according to Atlassian guidelines and also implemented our own browser caching of static resources.