Edit docs/maintenance-upgrading-services.md: add details about the difference between install-all and setup-all in speed

Also: remove the redundant description about that difference from description about the "just" shortcuts.

Signed-off-by: Suguru Hirahara <acioustick@noreply.codeberg.org>

docs/maintenance-upgrading-services.md

@@ -47,9 +47,9 @@ ansible-playbook -i inventory/hosts setup.yml --tags=setup-all,ensure-matrix-use
 
 - The `ensure-matrix-users-created` playbook tag makes the playbook automatically create the bot's user account, if any.
 
-- The shortcut commands with the [`just` program](just.md) are also available: `just install-all` or `just setup-all`
+- Our estimation is that running `--tags=install-all,start` is approximately from **2 to 5 times faster** than running `setup-all,ensure-matrix-users-created,start`. See [this entry](../CHANGELOG.md#2x-5x-performance-improvements-in-playbook-runtime) on `CHANGELOG.md` for more information.
 
-  `just install-all` is useful for maintaining your setup quickly when its components remain unchanged. If you adjust your `vars.yml` to remove other components, you'd need to run `just setup-all`, or these components will still remain installed. Note these shortcuts run the `ensure-matrix-users-created` tag too.
+- The shortcut commands with the [`just` program](just.md) are also available: `just install-all` or `just setup-all`. Note these shortcuts run the `ensure-matrix-users-created` tag too.
 
 - See [this page on the playbook tags](playbook-tags.md) for more information about those tags.