Why does searching message using filter in Special:Translate is very slow, comparing to Special:Search or Special:SearchTranslations which is very fast? Could it be improved to as fast as the Special:Search?
The filtering on Special:Translate filters the list of loaded messages. The other search pages can use the search backend to only return matching results. Making Special:Translate filtering faster would be a considerable amount of work, so I just suggest to use Special:SearchTranslations.
Could you make Special:SearchTranslations to show the pairs of english and selected language side by side in search result like this?