I can't tip either because the tables either don't load or take a very long time to load. I made sure all my neighbors on my Droid game were aware that I wouldn't be able to tip them. Earlier when I was doing the goal to go to 20 community members, I had to close out the game after going to 3 of them because the game would lag and the background would turn black. I'd clear the cache of 20+ mb then go back in and start all over again.
I can play with no problem if I just clear my appliances and put more food on, but to tip neighbors, nope I can't do it. It isn't just RS either, I can't LIKE in Fashion or Water in Farm as the racks/counters/plots/trees don't load and I just see floating water drops or floating thumbs.
Try playing tomorrow, all day, without attempting to go to your neighbors to tip and see if the game force closes on you. Also, make sure you have all non-critical apps stopped before playing.