On DXP 7.0, 7.1, 7.2, 7.3 and current master @ e19db256a248bcafb77a652f8b7e3faa8227c527e925d4fc436652a8932bdaf9 there will be performance issues while working on the miller columns representing a large page tree with several pages-sub-pages structure.
Consider the below scenario:
Then, click on /Level2
Expected: Subpage1,2 ..., 100 to load in a reasonable amount of time, UI to be responsive, no errors in the console
Actual behavior: UI will be unresponsive, then the page subtree will load after some seconds on this network request:
Even after the XHR request is complete, pages won't still be visible for some time.
The performance lag will become more and more visible as the number of sub-pages increases.
On 6.2, we had a "Load more" / lazy load mechanism that could hide the pages in case the tree was large, that could preserve the performance. On 7.1+, this is no longer existing as the Page tree is now represented in the Miller Columns layout. This, added to the fact that Liferay allows adding a virtually unlimited number of pages, will lead to the above explained performance behavior.
Liferay DXP should have a feature that allows to preserve the performance even on large page trees with several sub-pages.