Can/should I delete this App EtreCheck is says is causing high CPU usage?

That would imply you have a web browser tab that is running Javascript excessively. What it is running would depend on which website you were visiting. Or worse you visited a site that is running crypto-mining javascript.

You can try quitting your web browser, and restarting without accessing the tab (or tabs) that were causing problems.

If just starting the web browser causes excessive CPU, then it is running the javascript out of the cache. If this is Safari, you quit Safari, and then re-launch Safari holding down the "Shift" key to clean the cache. If it is a different browser, you will have to find out what that web browser does to clear the cache.

That’s usually a browser tab that’s gotten pretty busy. See which tabs are active, and maybe close them?

Please post the EtreCheck report here. Open a new reply, and then press the button that looks like a printed page, and then paste the complete hardware and software configuration report into the text input box that that button opens.

Common suspects when things go weird are add-on anti-malware, add-on anti-virus, add-on cleaning apps, add-on VPN clients, and add-on network firewall-and-monitoring packages. Ad blockers are another potential option here.

Alas, your proposed approach—trying to run without JavaScript, and not cleaning up add-ons—will usually be untenable, ineffective, unpleasant, and unworkable. A Mac infested is a Mac unstable and often increasingly unusable.