According to Apple, the reason they throttled older iPhones with aging batteries is because they were worried that users would experience unexpected shutdowns and reboots. However this resulted in phones becoming slower as they got older due to batteries degrading even further with each and every use.
However Apple decided to launch a battery replacement program as a form of an apology and if you’re wondering if you should take part in it, you probably should as the video above uploaded by YouTuber Bennett Sorbo (via 9to5Mac) shows off the iPhone 6s’ performance before and after the battery is replaced. Based on what we can see, the difference is like night and day.
Apps and websites would take considerably faster to load, and while they are only seconds apart, over time and over the course of the day, this will add up to an overall frustrating user experience. This is proven towards the end of the video where in total, the iPhone 6s with the old battery took a good 1 minute 12 seconds longer to complete the same circuit of apps and websites compared to after its battery has been replaced.
Note that even if you do not replace your battery, the upcoming iOS 11.3 update is expected to allow users to disable throttling, although like we said this will come at the possible risk of unexpected shutdowns and reboots, depending on how badly degraded your battery is.