[capink]

I never used this plugin before, but looking at the screenshots and taking a peek at the code, it seems to be using the same ImageComboBox in other kiwidude plugins I used.

I suspect, but not totally sure, that the problem might be related to this combobox.

The problem is that it loads the whole icon set for every entry in the table. So if have a lot of entries + huge number of icons in the resource directory, it can hog down the system.

I have noticed a lag when opening the customize dialog in the Open With plugin, on which actions chains dialog was based. I had solution that improved this for my plugin by caching the icons and re-using them.

Note that the problem is compounded by having a very large resources/images directory, which can happen if you are using the a custom icon theme. And becomes worse with adding more entries to the table.

How many rows you have in your config table? How many icons you have in the resource directory? Are you using a custom icon theme?

If you are using a custom icon theme rename the resources/images directory, which should make calibre revert to the default them (and deprive the combobox from those icons), and see whether that makes a difference.

Edit: Another possible fix for this is cleaning the json file from unused entries. Note that removing the json file altogether might not work, because the plugin seems to create huge number of default entries, and those need to be remove.