I've been having a recurring issue on my Minecraft worlds that cause chunks to load extremely slow when moving in a boat in oceans and occasionally on land or flying at full speed in creative.

Render distance setting, texture pack, fancy graphics and beautiful skies has no effect as my game isn't laggy.

Pausing, looking straight down or straight up and even relogging help for two or three chunks but it continues to not load for a very long time after that.

Side note: this is happening on my iPhone 7 Plus (there isn't an option for my phone in devices).