I've integrated Tags Bundle into eZ Platform Admin UI by extending "@eZPlatformAdminUI/layout.html.twig" template.

However, there is a noticable delay in rendering parts of the markup in the page and it seems it has to do with a call to "/js/routing?callback=fos.Router.setData". This call is relatively slow (response time of 4 seconds), and my markup will not show up until this call is executed, meaning very slow refresh times for Tags Bundle admin pages.