Optimizing Ubuntu Droplet CPU spikes for a high-traffic download site?

Hey everyone,

I recently migrated to a fresh Ubuntu Droplet. The site runs on WordPress with Nginx, PHP-FPM, MariaDB, Cloudflare, and Redis object caching.

Overall, page load times are good, but I’ve noticed occasional CPU spikes during traffic surges, especially after Google recrawls a large number of pages or when multiple visitors download files at the same time. CPU usage can briefly reach 100% before returning to normal.

Before I simply upgrade the Droplet, I’d like to make sure the server is configured properly.

A few questions for those managing busy WordPress sites:

• What PHP-FPM settings (such as pm.max_children, pm.max_requests, and pm.process_idle_timeout) have worked well for high-traffic websites?
• Are there any Nginx or MariaDB optimizations that made a noticeable difference in reducing CPU usage?
• Is Redis object caching enough, or is there additional server-side caching worth implementing for a mostly static content site?
• Which monitoring metrics or alerts do you rely on to distinguish normal traffic spikes from actual performance issues?
• Are there any common Ubuntu or DigitalOcean optimizations that people often overlook?

I’d appreciate hearing what has worked for others before I decide whether to scale the server. Thanks!