I appreciated your support.
I was a bit stuck for time yesterday, and didnt fancy developing the whole map in codepen, however, I've just added the very basics i.e. just a background image with draggable enabled, and I immediately have issues with speed in ios.
You can see the pen here
As you can see, it's a really simple set up - a 3000px wide map, that you can drag around within your viewport. The live map has loads of vehicles moving around the map (all being transformed, rather than being move via left/right etc), so they will likely slow things down a little, however I dont understand why there's such a difference in response speed when you compare iOS to Android.
Again, really appreciate any assistance you're able to provide.