Nephew and i upgraded our devices (his kindle fire and my LG G2, also the HP Probook 4545s hosting the game) to 0.14.1 and built several structures (survival multiplayer), including a hopper-clock assisted semi-auto Cow breeder/cooker and a Torch Burnout Clock assisted Automatic Chicken cooker, a couple buildings with about 30 double chests and an auto-smelter (chests on hoppers pointing into and out of 2 furnaces). Whenever either of us log in (whether on LAN or over the internet), there is massive...block lag? I don't know the term to use. Example: breaking hay, blocks or slashing a mob with a sword, literally it takes MINUTES for the action to register on said blocks and entities - on our mobile devices. On the host Laptop, everything happens real-time.
Tested with several routers and internet connections. Even bought an LG Sunset (pay as you go phone) and installed mcpe fresh from factory reset. Also turned all graphics settings to minimum on all devices. There's no relief. On 0.13.0 (granted, there were no redstone contraptions) we only had issues when there were tons of mobs spawning (like a huge 100+ flock of bats in the mine...) and a hunting expedition cleared that up.