Ever since 1.13 came out, Minecraft has been very laggy ever since. It lags easily, there’s lag spikes that comes out of nowhere, chunk loading causes a ton of lag, and gameplay is not smooth. The game lags the most on mobile devices and low end devices, on some low end devices, the lag is so bad that it runs below 10 FPS causing the game to become unplayable. The FPS drops very easily during gameplay, and having render distance maxed causes lag. In 1.12, having render distance maxed, the game would not lag at all. The FPS would not drop easily. And the game would not lag on mobile and low end devices. Chunk loading would not cause the game to lag and gameplay is smooth. But after 1.13, gameplay is not smooth at all. 

Is you are having issues with lag and low frame rate, then please UPVOTE THIS BUG REPORT so Minecraft can be optimized back to 1.12 standards.

Here is 3 videos of me demonstrating of how the game runs with max render distance in a fresh new world with different simulation distances.

These videos were filmed from an iPad 7th generation