Elementor is the more common of the two in our index: it runs on 1,374 websites against 147 for Perfmatters, and 29 sites use both. Counts come from real scans, not vendor claims.
Elementor is a website builder platform for professionals on WordPress.
Perfmatters is a performance optimisation plugin for WordPress websites.
29 sites run both Elementor and Perfmatters. That is 20% of the sites using Perfmatters, the smaller of the two.
Want to know which one a particular site uses? Look it up and see its whole stack, or compare two sites side by side.