Find and replace (regex) takes mutch longer with \n

Wen i use find and replace in kate on a large amount of lines (1.9 M in this case) it takes basically for ever if i use a regex that ends with “\n” to replace the entire line and not just the content. To apply the regex with out “\n” it takes a few seconds but if i add “\n” to the end even the “Alle suchen” [“Search all” or so] will not complete in a reasonable time. I tried it with 40k Lines and it took over 1 min. Is this a bug that I should report or is it a lot harder to match with “\n” in the regex? Adding “^” at the beginning dose not seam to improve the situation. Thanks for help in advance.