Hi, many thanks for this app. I've been using it for about two years and find it extremely useful. Great job!
The bad thing is the recent update (v.4.1.5). It has made the writing game quite a bit slower (have not yet checked with other games). Here is what happens. I am used to review cards in thousands. For example now I review about 3000 cards, divided into 50 sections. I pick up all 50 sections and start the game. Before the update it turned on almost immediately. Now it takes about a minute to start.
Inside the game similar thing happens: writing and browsing between the cards goes instantly from the beginning, but after a number of cards it freezes for about 30 sec and only after that continue. I noticed that freezing happens each time, when the app returns to the card already reviewed. I mean it looks like it freezes, when it needs to calculate to which card it should return (because it needs to go back time and again to show you each card the required number of times). I am not sure if it explains the issue. Sorry, English is not my native language.
My guess is that the issue is due to the new algorithm of Leitner realized (as I understand) in the update. In shuffle mode the problem does not seem to appear. Would it be possible to add into "Settings" --> "Card order" the option like "Previous Leitner SRS"? I would happily use that one (not only because it did not freeze, but because I liked when the cards were of different levels).