Is it normal if a WordPress site becomes slow after installing SSL?

 Does SSL make website slow?Yes, it's true that SSL can impact the performance of your website.

But its efforts are so minor that saving a few milliseconds won't outweigh the increased level of security that SSL affords. With HTTP/2, HTTPS is only getting faster so any performance impact SSL adds to connections is dropping fast.

How does SSL affect website performance?

When the page has SSL enabled, it requires extra round trips to establish a secure connection which impacts the site performance. Studies comparing HTTP/2 vs regular HTTPS transactions show that HTTP/2 is faster and more efficient as it allows multiplexing which has a positive impact on the page performance.

In general it depends on the specific site limitations but the speed can be improved