How can I disable the fade in and fade out effects in pgAdmin 4 when opening windows?
I could not disable the fade completely, but I got to remove the zooming effect (which also executes faster) improving the user experience. The zooming effect is added by AlertifyJS. 

Edit the file alertify.pgadmin.defaults.js file located in C:\Program Files (x86)\pgAdmin 4\v1\web\pgadmin\static\js

Then change 

alertify.defaults.transition = "zoom"; 


to 

alertify.defaults.transition = "fade";


After making these changes, restart pgAdmin4 or click on File > Reset Layout.

Hopefully this step assists someone to find a better solution...

One can also set the above option to none, in this case it seems to default to the pulse transition.