This game is playable on a Nexus 6, but suboptimal. Screens like the main menu, map, etc. are fast, but when it comes to my collection, it slows down to a crawl. Idling on the Team screen (after you click on the Team button) puts me at under 20 FPS. Dragging and dropping is also sluggish. I don't even have 300 fighters. If I click on a character and go back to this Team screen, it can take up to 8 seconds for me before I'm able to continue.
A way to boost performance on this screen would be to preserve user filters and also modify the character list to auto-filter out ineligible characters. If a team requirement is "Bronze Only", it's not helpful for the game to show me my silver and gold characters. If the team requirement is "Cerebella only", then just show me my Cerebellas.
Frame drops in fights are another issue. They interrupt my inputs as well, mostly when I perform a launcher after a ground combo. If my phone is lagging, the launcher does not come out, and I get hit. In general, the more assets there are on the screen, the more slower a fight is. I.e. Parasoul's BB3, Peacock's Argus Agony. Tag ins also cause the game to slow down noticeably, so the pacing of fights feels very off at times.