Latest versions cause high memory usage and 503 errors

Versions newer than 6.2.0 are causing big memory usage that ultimately results in 503 errors (my server uses Cloudlinux).

The problem is instant: disabling the plugin, the site loads normally. Enabling the plugin, the frontpage of the site doesn’t even load.

I’ve increased the WP memory limit to 1024 MB and the problem still happens. My host has increased my (already generous) memory allocation, it doesn’t fix the problem.