Very laggy on some worlds

The MCCE mod told me to recreate this ticket according to the Issue guidelines.

Title says it all - it's very laggy. I only tested this on one world, but I have more than one that's very laggy.

Here's a download link to the affected world.

and try to copy it to another PS Vita for testing.

Tried the world on my PS3 and it is SO laggy...

The Nether isn't laggy; dragon's breath as an entity does.