On Windows by default search bar will take 1-3 seconds to load. Hovewer it is possible to enable instant search bar.
Search bar will be loaded instantly.
Premiere Pro UI might flash after you execute Excalibur command. From my test it happens when you have another application window behind Premiere Pro.
There is a bug in Premiere API that wont allow to use Japanese or other languages that use IME in a search bar.
Panel mode is primarly made as a workaround for those cases. Drawback would be that panel size can't be defined by user. As a benefit: the panel could be placed anywhere on a screen and its position will be remembered.