I was tinkering with the settings of my Galaxy S6, which has been getting a little sluggish in its old age, and the below adjustment has MASSIVELY improved its general responsiveness. It is absurdly quick now (apps open and switch much quicker) for no good reason that I can discern.
Anyway, perhaps others with this phone would like to try this alteration and see what happens. Would be interested to hear if others have a similar result.
FYI I'm running Android 6.0.1 on Vodafone with all the latest OTA updates installed. Not rooted, no mods or anything custom on it.
1. Go to settings, about device, software info and tap the 'build number' bar 10 times. This will unlock developer settings.
2. Go back to main settings, scroll to the bottom and open 'developer options' and move the slider at the top to 'on'.
3. About 2/3 of the way down you'll see 'window animation scale', 'transition animation scale' and 'animator duration scale' - these should all be set to 1x by default.
4. Change each of these to 0.5x and press home.
You should thereafter notice that animations behave a bit differently, and for me at least, the phone performs noticeably better.