Board Thread:Tapped Out Help/@comment-25077005-20160601195002/@comment-26143371-20160603230527

Is it only one friend, or all of them? If it's only one, them his/her town is probably too big for you're device to handle. IN that case you can either hope for EA to improve performance or get a newer device. Otherwise you won't be able to visit your friend reliably.

If it's a general issue for all friends, try the following :
 * clear your cache (if you're on android)
 * reboot your phone/tablet
 * reinstall TSTO

Even though crashes and freezes happen from time to time in this game, I haven't heard of any widespread issues with that lately, and don't experience them myself. So this is probably specific to your device and/or town.

If nothing of the above helps you can always contact EA through. But I wouldn't expect too much from it...