How to optimize server load with a WordPress blog?

Question

PHP

I have a WordPress blog hosted on the first DigitalOcean plan (1xCPU, 512MB RAM).
Sometimes, after publishing an entry and sharing it in social networks (more than 200k followers), there is a sharp surge in visits.
The Nginx + PHP-FPM bundle is used. How can you correctly tune the server so that it does not choke on a sudden load?
Stably starts working when the number of users drops to 600-700. At 1000+, it starts to lag and give the page for a long time.

Answer 1

caching, put some w3total cache or something like that (I think it will be bold to put a front-end on such a tariff). Let WP generate HTML and save it, and then let nginx give the static to the fans. Then requests will not reach PHP at all.

Answer 2

Cloud Flare!