I had the same issue. Reported it, and got a reply saying it was invalid. Great that it's still not fixed after 2 months.
There are lags constantly even when walking on overworld in any type of biome, holding nothing, with 0 inventory, and with various naturally spawned mobs or animals.
Is it possible that this report didn't mention it is a bug presented on the mobile Android version that Mojang didn't refer to the correct version to reproduce the bug?