Do too many apps slow my store down?

They can. Many apps inject scripts into every page, and each one adds load time — which costs conversion. Two habits keep it in check: audit the stack quarterly and uninstall anything you have not opened in a month (uninstall fully, since some apps leave code behind), and prefer apps that load only where they are used. If a page builder or review widget is on a money page, test the page speed before and after installing.