Serving Scaled Images

I see the members directory resizes the profile photo to 90×90 when a cover photo is shown as well.

I added a 90 profile photo thumbnail size in General > Uploads.

However, rather than serving that 90, it resizes the default uploaded photo to 90.

I’d prefer to serve the scaled images to increase my speed.

How can I make the member directory locate and serve the 90?

Thanks!