Although it’s an uncommon issue and happens randomly, sometimes when trying to edit your galleries your browser will freeze and you may get a yellow bar in the browser window saying a script is slowing down the page – like in the screenshot below.
This issue seems to be user related and it will most likely happen only to your user.
If this happens, you will need to edit/replace a file in the plugin with the one below.
To do this please download the corrected file from here: https://www.dropbox.com/s/gqmqkrkxn04azv2/wp-modula-settings.js?dl=0
Then go to this file: assets/js/admin/wp-modula-settings.js
And replace it with the one above. This should fix the issue.
Make sure to backup your site before you make the change, just in case.