edge keeps running in background regardless of settings

First of all, yes, I have already disabled 'speed boost' and turned off the setting that allows extensions and apps to continue running after closing edge, and still when I look at the running tasks there are multiple edge processes there (sleeping or otherwise) after exiting.

This is obviously an unnecessary waste of memory and processor resources etc., but what is much worse than this is that any credentials established with websites using integrated authentication are  also maintained and used again when the browser is re-launched.

So if multiple people are using a machine and one authenticates against a website using integrated authentication and then they close the browser and leave, their credentials are applied when whoever uses the machine next accesses that same site.

This would seem to be a fairly serious security issue, and I have submitted this as a bug through the browser's feedback mechanisms, but has anyone else experienced this and/or found a solution?