Within the developer options, consider enabling 'Force GPU rendering', followed by a restart. On my Nexus 6P, this significantly improved UI responsiveness, bri

Within the developer options, consider enabling 'Force GPU rendering', followed by a restart. On my Nexus 6P, this significantly improved UI responsiveness, bringing it closer to that of the iPhone 6s. Scrolling, zooming, and app switching are now silky, or "buttery", smooth. My friend with a Nexus 5X, however, noted only a marginal improvement; so your mileage may vary.