Opening the cross reference panel can be painfully slow. This has been an issue since at least InDesign CC, but maybe now is another chance to fix this.

Behaviour is triggered by size of document and/or number of cross references. E.g. I'm working on a ~200+ pages document with about 150 cross references – both of which isn’t that extreme – and opening the panel takes around 4 minutes (yes, minutes). Interestingly enough, if the panel once opens and I change "Link to" from "paragraph style" to "text anchor", next time the panel opens instantly. Change it back to "paragraph style", go get a coffee in the meantime. As a workaround I split up the document into several documents and put them together in a book. In these smaller docs, opening the panel is more or less instant. However, managing books is not without other drawbacks and using only text anchors for cross references is limiting for no good reason. Pleas, fix this this time around.