Oops, posted at the same time!
The newer script has more features, eg you can use tags in layer names like [skin] or [merge] or [bone], which can be very useful:
spine-scripts/photoshop at master · EsotericSoftware/spine-scripts
First though, are you sure you have the latest script? Right click this link and choose Save As
. If you open with a text editor, at the top of the script you should see scriptVersion = 3.0
(or higher).
The focus seems to only be a problem in some Photoshop versions. The script tries to put the progress bar window on top of the script dialog, but in some Photoshop versions apparently this focuses the whole window.
The speed should be the same or similar to the old script. How much slower? We're mostly at the mercy of Photoshop here.
We'll look into improving these two thing after you verify you are seeing the problem with the latest script.