When the plugin needs more more RAM memory? When plugin compiled (*.phar) or not (plugin/scr/plugin/*.php) ?
Files inside a phar are loaded faster than file in your filesystem, so phar is better. But in terms of RAM, I don't think there is a lot of difference. @Kvetinac97 we are discussing about the difference caused by the plugin loading itself, not by the method to load the plugin. DevTools is not the only method to load source plugins, and loading DevTools has extremely negligible effect of both RAM and performance.