Hey,
Thank you so much for your feedback.
We’d be happy to help you if you provide us with more information about what report or tooling you used to measure performance.
As for the recent version 1.29.0 we didn’t add such stuff that can directly impact on website page performance.
If you don’t mind one thing I want to add, Site Kit doesn’t add any performance impacting code to a users site, if you check your sites source code before and after installing, activating and setting up Site Kit you’ll notice only one meta tag link added, as below:
<meta name="generator" content="Site Kit by Google 1.26.0" />
The above snippet does not have any impact on performance. Site Kit is primarily an admin panel operated plugin, allowing for the automatic insertion of various Google product snippets at the users preference, without any manual placement of code.
Happy Monday!