What app is showing these fix now messages on galaxy s6? I have a Samsung Galaxy s6 that sometimes will pop up a message suggesting that some apps are consuming too much ram or cpu. And the following screen. I haven't been able to figure out what app it is though that seems to be acting like good samaritan on my phone.

It doesn't show on recent apps list and once I tell it to perform the fix, i can't interact with app or go back to it.
Install Shutapp from play store and close all opened applications through it, you'll see all the opened apps and doing this may fix your problem. Find the conflicting one. If it's not a system application, you'll see it in the list. Also, You can click just below the big circle to see the list without closing the apps. Check whether that list has any unknown app.