Walkthrough images load slowly

[daviddossett]

Ref #165846

The SVGs in our built-in walkthroughs load quite slowly—and occasionally not at all—even on a fast machine. This isn't so bad, but it can be far slower on a slower or already-busy computer:

CleanShot.2022-11-21.at.10.57.41.mp4

Wondering if there are any quick wins here. The slight delay makes the whole experience feel sluggish and old.

@esonnino