Actually no!

The plugin is tuned for maximum page performance with no bloat, no external libraries, no tracking.
In all tests I’ve conducted on various websites, I have literally seen absolute no performance decrease at all. Give it a try yourself!

The details: The plugin adds a single line of CSS to your page source code. Additionally, a minified JS and a very basic CSS file is loaded on the first page visit. All files are less than 7 kB in size and are cached by the browser. Trust me, your visitors will not notice anything.