The plugin has some nice features but there is a major flaw:

Although we deactivated the standard TOC completly and only activated the sticky TOC and also only for posts, the functions seem still to run on our homepage. I deeply tested it. When sticky TOC is activated (only for posts), our hompage loading time piles up from 1s to 2,8s which is an insane increase. I tested multiple times. I also deactivated the plugin completely and the results are the same.

The plugin adds then the class “ez-toc-section” to every header like h1, h2, etc. It seems it is duplicating the whole page before it is thrown out, that´s while page load almost triples. I asked the support, even send a video, but it seems the support has no technical knowledge, so you kind of walk in circles with them without a result.

For me personally this invasive behavior is too much. Sticky TOC shouldn´t run on homepage or other pages when it´s deactivated. And I mean really shouldn´t run the functions, not only hiding elements via CSS if that´s the case.

A better solution would be they would wrap their functions and run them only on desired posts, pages, etc. for example with:

function my_custom_function_for_single_posts() {
    if (is_single()) {
        // Your function or code to run only on post pages
    }
}
add_action('wp_head', 'my_custom_function_for_single_posts');

But I´m not completly sure were their problem really comes from. Perhaps they will fix it in future. For everyone until now I recommend test you page loading times, with and without activated plugin, to be sure that your site won´t be affected badly.

Regards