@franz-wohlkoenig Is this only happening in Weblinks, or in other places as well? If it's only weblinks this PR might be better suited elsewhere since it's been decoupled, but I'm not entirely sure and I'm not seeing this issue anywhere else. Let me know.

@cpfeifer weblinks was Example. Tried in "Article > Tag", "Contacts > Tag" there is a Judder.

Its not in an Lightbox like "Select Menu Item Type".

Thank you for the clarification, I wasn't seeing what you were describing. Are you testing on the most current version? The interface fields and display have been updated and look different from what is seen in your post. I am not experiencing the issue in the tag selection or any other selection in the alpha release. Can you please take another look and let me know. Thank you.

I'm on Joomla! 3.7.0-alpha1, Firefox 50.1, macOS Sierra (10.12.2) with this Result:

Thanks for clarifying again. It appears to be isolated to Firefox. I'm seeing the issue there and getting this in the console.

JQMIGRATE: Migrate is installed, version 1.4.1 jquery-migrate.min.js:2:542
Use of getAttributeNode() is deprecated. Use getAttribute() instead. jquery-migrate.min.js:2:1714

This site appears to use a scroll-linked positioning effect. 
This may not work well with asynchronous panning; see https://developer.mozilla.org/docs/Mozilla/Performance/ScrollLinkedEffects 
for further details and to join the discussion on related tools and features!

At least we have some clues to help us solve the issue. I'm sure it's fixable but I'll need to look into the code a bit.

Thanks for Answers Cliff, hope the Issue get solved.

@dgt41 - Is this something you can help with?

@cpfeifer you need a CSS expert here, I think

@dgt41 There is a jQuery error in Firefox. I'm sure I can figure it out but maybe you know how to fix it faster.

`JQMIGRATE: Migrate is installed, version 1.4.1 jquery-migrate.min.js:2:542
Use of getAttributeNode() is deprecated. Use getAttribute() instead. jquery-migrate.min.js:2:1714

This site appears to use a scroll-linked positioning effect.
This may not work well with asynchronous panning; see https://developer.mozilla.org/docs/Mozilla/Performance/ScrollLinkedEffects
for further details and to join the discussion on related tools and features!`

That's from jquery-migrate.js and is not an error it's a notification about deprecated code. Joomla 4 will drop this script

Thank you. JS is not my strong point, but I think it's related to the issue at hand. Just wondering if you had any ideas, I don't think it's CSS in this case.

Try the original CSS from chosen. Is scrolling smooth with that CSS? If not open an issue to chosen's repo

It's the same with the original CSS, and on their demo page. https://harvesthq.github.io/chosen/

It appears to be a general Firefox issue, they have a lot of docs about janky scrolling with suggestions leading to this doc: https://developer.mozilla.org/en-US/docs/Web/CSS/scroll-behavior

None of the fixes I tried had any effect. I'm not sure what we can do, but it's definitely not an issue with our code.

@cpfeifer As this Issue don't depend on Joomla i close.