This v-sync is probably the reason why it's 720p docked, and has a lower render distance when undocked.
On average, Minecraft on Switch could mantain a higher average framerate than Wii U (even undocked), but this isn't apparent because the Wii U version doesn't drop straight down to 30fps!
Performance can be cut nearly in half cases where every frame takes just a little longer than 16.67 ms (1/60th of a second). In such a case, frame rate would drop to 30 FPS despite the fact that the game should run at just under 60 FPS.
When something only slightly intense happens, the game just immediately dips to 30fps regardless.
Play in undocked mode and head to a jungle.
This v-sync is probably the reason why it's 720p docked, and has a lower render distance when undocked.
On average, Minecraft on Switch could mantain a higher average framerate than Wii U (even undocked), but this isn't apparent because the Wii U version doesn't drop straight down to 30fps!
Anandtech explains this properly
http://www.anandtech.com/show/2794/2
are you still having this problem, sometimes I get it too