No offense, I had to try that..

https://upload.wikimedia.org/wikipedia/commons/3/3d/LARGE_el...

Look how fast and responsive it is!

With progressive decoding and spatial range requests this could actually be a reasonable replacement for a slippy map.

I'll use it on my drive home.

That supports touch zoom just fine, it just has a low limit to how far in it goes.

Obtaining the zoom level is an adventure worse than implementing multi-touch-twist-and-shout-zoom from scratch.