Page tree XHR is fetching huge JSON data
Maintaining a website with over 100.000 pages I've noticed the page tree, which is claimed to be fast, becomes extremely slow on big TYPO3 instances. This is due to the fact the whole tree is fetched and send to the browser as JSON. Each page record takes approximately 1000 bytes of data in JSON, so the JSON return of 100.000 pages is 100 Megabytes. That takes a while to download. At a 100 mbps connection that will take like 8 seconds. TYPO3 version 8 did not have this problem, because only data which was needed was fetched. If you had a node closed, no data for the subpages was fetched at all.