On MATE under 20.04.1 LTS (as well as previous LTS releases that I have tried), the GUI arrow (on-screen activation pointer) that one positions over a desktop icon for an executable application becomes a small circular spinning icon whilst the application is "loading" but not yet visible on the screen for SOME applications, but not all. Is there a setting that will force the spinning or other waiting/loading icon to appear as an application initiates? I suspect that this behavior is common to all of the Ubuntu GUI windowing environments. I note that under EL (not LTS) for all the major releases I have used, either with MATE, "old" Gnome, or "old" KDE, an equivalent waiting icon was shown for all applications that were selected for use but not yet "loaded". Note that I posted the same question to the Ask Ubuntu list but it was suggested to repost to the specialised Ubunutu MATE list as well. (I find it most wasteful that this sort of thing is not cross-listed rather than requiring a separate new account and copying and pasting, but that is the way these lists were constructed.)
Look at files in /usr/share/applications/ (for all users)
and files in ~/.local/share/applications/ (for your user)
These are .desktop files for applications that you can open with a text editor (Pluma).
Look for the line:
StartupNotify=false
If this line is set to "false" (as above) there won't be a spinning cursor, but if it is set to "true" there will be spinning cursor animation.
At least this is how it works in Xfce.
The above also works on MATE, U 20.04.1 LTS. Note that for some applications, such as Thunderbird for which I setup a number of profiles, until the profile selector appears, the Startup Notifier (spinning symbol) appears, but after the profile selector selection has been made until Thunderbird actually appears, there is no indication that anything is happening except for the hard drive hardware indicator on my machine. Presumably, with a SSD and not an electromechanical magnetic storage hard drive, the latency for the display of anything would be negligible.