Thanks so much for this great feedback! I haven't done any speed optimization on portray yet - as both at work and online I tend to organize my own projects as small self contained repositories. Clearly there is a lot of room for improvement there, I have a lot of ideas to make it faster.
You can manually define the modules for portray (which you probably figured out to get documentation rendering): https://timothycrosley.github.io/portray/docs/quick_start/4....
And, yes write now Markdown only. I will say - this was a week only project: https://timothycrosley.com/project-2-portray so I think there's a good chance I could improve these points with one more week of time spent :)
Thanks!
~Timothy