TLS performance: rustls vs. OpenSSL, https://jbp.io/2019/07/01/rustls-vs-openssl-performance.html.
rustls is:
• 15% | 5% quicker to send | receive data
• 20-40% | 10% " to connect a client | a server
• 30-70% | 10-20% " to resume a client | a server
• uses less than 50% the memory of OpenSSL