The Lower the Storage, the Slower the Performance (Over Time)

At first, all new iPhones seem to be performance beasts that can handle multiple tasks without breaking a sweat, but that will not always be the case.
Over time, your iPhone will start to slow down, and you’ll need to perform maintenance to boost its performance again. One of the tips you always hear is to free up some storage space.
When available storage drops below a certain threshold, your iPhone’s performance will suffer. Generally, it’s recommended to have at least 10% of storage free at all times so your iPhone can maintain optimal performance.
Free storage can be difficult with an iPhone’s only 128 GB, so you should consider getting at least a 256 GB model.