TL;DR - There is an online test site, so you can quickly compare HTTP vs. HTTPS performance by yourself:
From August 19th 2020, SECTIGO issues SSL certificates with a maximum lifetime of 398 days (13 months) as specified by CA/Browser consortium. SSL certificates with a longer lifetime must be re-issued annually (free of charge). You'll receive reminders via e-mail. SSL certificates issued before August 19th 2020 remain valid until their planned expiry date. Code Signing & S/MIME certificates are not affected and remain valid until their planned expiry date.
Why HTTPS is in fact faster than HTTP, not slower?
Troy Hunt has released an article about this topic. The live-test compares loading images via HTTPS and HTTP. He shows that HTTPS is loading about 80% faster than HTTP. Read more here: https://www.troyhunt.com/i-wanna-go-fast-https-massive-speed-advantage/
