Large effect stacks break the game play
Right now, my game has been on auto for 10 minutes because I have Soul Warden + Cleric (and Elesh Norn), while my opponent is cranking out 99 Goblins with Krenko, Mob boss.
This process is super slow. There needs to be a way to deal with large triggers in mass, rather than being super slow and timing out. I can tap assign each extra +1/+1 counter as soon as the UI lets me, and it's still eventually times out and takes about 6 seconds to process each of the almost 200 events.
If this were an actual game, my opponent would probably just write down on a piece of paper "I have 99 goblins" and I would write down "I put 50+1 counters on this creature, and 50 on that..." This is an instance where gameplay is much, much, much slower on the computer than in real life.
In fact, I think my opponent's strategy is to try to get the game to time out on me rather than actually winning, because he doesn't bother attacking and he keeps pumping out goblins.