I've been testing seeds in creative mode and flying around to see if anything is interesting near spawns. For all biomes other than extreme hills, my tablet renders pretty quickly, with some minor slowdown. For deep ocean biome chunks, the rendering can just pause for 5 - 30 seconds.

I've noticed that crossing oceans in survival mode in a boat also can't seem to keep up rendering chunks as fast as I can move and frequently have to wait a similar amount of time for the renderer to catch up.