The iPhone SE might come in a small package, but don't let that fool you. The device's performance is on par with the iPhone 6s' and exceeds that of the iPhone 5s and iPhone 5.
If you're looking for a boost to your performance, whether it's from a battery life standpoint or a gaming standpoint, look no further than the iPhone SE.
Again, the iPhone SE comes with the same 64-bit A9 chip and M9 motion co-processor as the iPhone 6s. These chips help the device outperform its predecessors in key areas like battery life and playing mobile games.
Simply put you'll get better battery life buying new phone because the device hasn't gone through the same number of charge cycles. If you own an old phone, your battery's degraded over time.