Let's Encrypt caches around 100k OCSP requests every second

"Since Let’s Encrypt serves 300 million domains, we cache around 100,000 OCSP requests every second. Historically, Let’s Encrypt could cache about 6% of this traffic on its own. But were we to experience traffic much higher than that, we’d risk Let’s Encrypt falling over. Not an ideal situation for us, or the Internet."

https://www.abetterinternet.org/documents/2022-ISRG-Annual-Report.pdf