Get simple 3.3.16 support for php 8.0

[Felix]

Page Management at the back end shows all the page titles within few seconds. Edit Page which contains more than 250 PDF pages content also open up within few seconds.

GS will stay very fast on the Front-End even with thousands of pages.
However, the GS Back-End was not made for so many pages.
The main issue is the page cache, as it is not an incremental cache,
its one large file and all pages have to be processed. Most People
are not aware of this and only find out after building so many pages.
Glad to hear that in your case the Back-End shows all the page titles
within few seconds which is still ok to work with.