Click here to see the Multi-Excerpt AddOn in the Atlassian Marketplace
The multi excerpt plugin behaves like the excerpt macro, but allows for multiple excerpts, from multiple spaces.
For several invocations of multiexcerpt-include on the same page will unfortunately result in degrading performance of rending of that page. The more multiexcerpt-includes the greater the performance degradation.
This is currently a limitation of the "Confluence Cloud platform" implementation by Atlassian and the way it is currently offered to add-on vendors. There is no way around it I'm aware of. We already do as much client side caching as we are able.
Thus if you are running into performance issues because of the need for many multiexcerpt-includes on a single page I highly recommend considering "Confluence Server" which can be hosted by a 3rd party who specialize in Confluence hosting such as Contegix or hosted by your IT department. You'll ultimately get more performance out of Confluence Server across the board and access to thousands more reliable add-ons.
and will post more information both here and there as we discover it and whether Atlassian provides a solution to this. Solutions such as using BigPipe would solve this problem.