Our potential issue we are seeing is since all users are allowed to see all management zones, if they click on "All", it causes a lot of lag which they start complaining that Dynatrace is "slow".
Do you know if there is a way to remove the "All" button so that a user can not click on All?
There is no such option to delete All button. This is important functionality in Dynatrace to be able to see all data as well.
As I understand you have large environment with multiple entities and there is lag while you are switching to all? In general there should be no such issue. Only smartScape may be here problematic, but this one should be filtered via Management Zone. Without this it may be hard to read.
As far as I am aware not all users see all management zones. Those users who are assigned only to a subset of management zones do see only those. Also the 'All' filter does filter only for those that your user is assigned to.
An example: You have 500 management zones. User 'Alice' sees only 3 of those. The top filter only shows 3 management zones and the 'All' filter only filters for those 3 zones, which is fast.
I think we were afraid people, who should have access to many different management zones, would inadvertently click on "All" and therefore cause backend performance issues or think Dynatrace was slow because they queried too much data.