Improve question "Why Tor is so slow"

Improve this answer: https://support.torproject.org/tbb/tbb-22/

with https://2019.www.torproject.org/docs/faq.html.en#WhySlow

• Add Roger's blog post
• Add What can you do to help?
• Tor design details
• See also: https://gitlab.torproject.org/web/community/issues/#94