Implement Feedback on Load and Performance doc

[rachelwhitton]

Re: #2140

Issue Description

First iteration of refactoring this doc has been deployed but there are loads of helpful comments and suggestions we need to circle back and implement.

Suggested Resolution

See related PR and work with EOMs to add the suggested changes.

[alexfornuto]

Re-opening as there are still some outstanding comments left to be addressed.

[erik-pantheon]

I'll take a look at it. :)

[alexfornuto]

The discussion in #2140 points to EOM as the best source for answers to the outstanding questions from Ari's feedback. I've reached out to @erik-pantheon to confirm if he's still reviewing, but until I hear back I would say this is open to any other SME interested.

cc @lauren-kelly @JessiFischer @adamedgmond @bentekwork