How can I optimize my WordPress site for slow speed, especially at high traffic?

In my experience, you can try using a CDN (Content Delivery Network), which spreads your site's resources across servers around the globe so it loads faster when users visit. Coupled with Lazy Load, which allows images and videos on a page to load only when the user sees them, it can greatly improve loading speed. Also, remember to clean your database regularly to get rid of unnecessary junk data. Finally, if all these are done or still stuck, then you can look at changing to a host that is more suitable for high traffic or optimize the server configuration. I hope these can help you speed up your website!