If your iPhone 6, 6+, 6s, or 6s+ is working slow then try this simple tweak to speed it right up.
Simply follow the directions:
Step One:
Tap on Settings

Step Two:
Tap on General

Step Three:
Tap on Accessibilty

Step Four:
Tap on Increase Contrast

Step Five:
Turn on Reduce Transparency

And that’s it! Your iPhone should now be working much faster.