GLTF import performance

[schell]

Importing bigger models can be pretty painful.

Here's a related thread on the gltf crate.

Here's a flamegraph of what I'm seeing:

To break it down:

• the first mountain is loading/transforming geometry from the gltf accessors
• the second mountain is image decoding

Image decoding is the bigger optimization opportunity, but it's internal to the gltf and image crates.

The geometry can definitely be optimized from within renderling so that should be the priority of this ticket.