You can't measure something without impacting it. Adding spyware to products make them slower.

Here is an alternative solution I begun using for one of my projects:

There is no telemetry like grep in nginx logs with carefully fetch()'ed paths.

Put this in JS code:

    fetch("/stats/user_used_feature_x") 
    fetch("/stats/user_reached_checkout_step_3") 
    etc.

Then you can find the information you need with:

    grep -o ".*/stats/[a-z_]*" /var/log/nginx/access.log

Now you can count how many users reach features and checkout steps.

That is dozens of time more performant than using third party scripts. No extra library.