Hi. I've checked the JS loaded by the plugin, and I suspect it being a malware, mainly because of the following section of code:
[ Suspected malware deleted, don't post that here ]
This piece of code, even beautified, seems to be think to be as unreadable as possible. Maybe I'm wrong, but if it's true, it does not follow the wordpress plugin development guide lines.
So, to allow me to understand your code and check that this script is senseful, please provide an unminified version, and the uglifier you used to reduce your scripts to check concordance.
This suspicion is even more increased by the fact that the GitHub user was deleted and is impossible to track. https://github.com/wp-plugins/wp-optimize-speed-by-xtraffic . Please answer quickly, or I'll have to notify to WP teams what I saw, and why this seems to not follow the rules.
Thank you for your attention.
https://wordpress.org/plugins/wp-optimize-speed-by-xtraffic/