It doesn't matter what connection I'm on, and the website is always instant, but the Android app always takes half a second to load any screen. It's infuriating when you want to view the analysis, or just navigate around the app.
My bug is about Puzzle Storm. When you run out of time, the GUI shows you the post game screen and it takes a fraction of a second before it pops in a "daily record" banner. This fraction of a second is slow enough for me to drag my mouse cursor over the "Failed puzzles" filter, but fast enough for me to accidentally click "Play again" as it has been pushed down the page (by the daily record div) without me perceiving it yet. Once clicked, that button resets the page to start another puzzle storm and by then I've lost the failed puzzle history, so I can't go over it anymore.
It has happened already in the hundreds of times. I can't help it, hopefully the dev one day figures it out.