As I predicted, exams caused a noticable slowdown. Which would've even been more severe had I not tweaked my learning routine a bit.
To save time I decided to stop writing out readings for recognition cards while continuing to write kanji + furigana for recall cards. Curious side effect: I have the feeling this helps me paying more attention to the correct pronunciation of words, since I have to verbalize the word in my head precisely in order to be able to compare my answer to the written solution in Anki. I guess coming up with an answer in a "verbalizing context" is somehow different to writing it down.
As for recall cards I started trying to always think of the pronunciation of a word first instead of the kanji. Reason: in conversations I need the pronunciation of a word immediately. When writing it is no problem to halt for a few seconds.
Two more weeks of exams to go. Won't manage to get to 1800 in 30 days I guess, but less than 45 should be doable. :)