This problem only seems to have gotten worse over time, but the current state of the Switch version of the game is "barely functional".
Start a new game
Leave all game settings at their default values
Walk / run anywhere for more than 2 or 3 seconds
Game is no longer able to keep up with chunk loading
Does not matter if you are playing survival or creative, though any faster than running movement (boat travel on water, creative flight, etc.) will show the problem even sooner.
Related issues
duplicates
Comments

Thank you for your report!
We're tracking this issue in MCPE-120971, so this ticket is being resolved and linked as a duplicate.
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