The I phone 5s runs apple’s a7 chip, which the company claimed was twice as fast as a6 but is hamstrung by paltry 1 gb ram. You will notice this the moment you open a few tabs on safari and try switching between them. Some of them will reload the entire webpage as the device does not have enough ram to keep those tabs in memory.
By and large, our iPhone 5s performs very well for a device of its age. We can not think of a single two-year-old device that would perform as well based on the experiences of our friends and family members.