See here - https://www.reddit.com/r/ProtonVPN/comments/1h7g8vs/why_in_the_name_of_god_proton_vpn_takes_so_fing/. Proton VPN uses hundreds of MB RAM. And lags horribly when opened.

Please investigate and fix this. I assume you're using some sort of HTML framework. Maybe swap to something designed for desktop and speed - like Avalonia or Flutter.