One of the improvements in iOS 9 concerns battery life, as Apple plans to further increase it with help of a Low Power mode that can be enabled at any time by the user when their remaining charge gets too low. However, don’t be surprised if your iPhone 6 or any iOS 9-ready device takes a pretty big performance hit once Low Power mode is enaled.

DON’T MISS: Did You Know Your iPhone Was Hiding These ‘Secret Tricks’?

Now that Geekbench 3 supports iOS 9, MacRumors compared the performance of the iPhone 6 running in regular and Low Power modes.

Unsurprisingly, iOS 9 will significantly reduce processor performance in order to increase battery life — Apple actually tells you that Low Power will not only reduce performance, but it’ll also disable mail fetching, background app refresh, motion effects and animated wallpapers.

ios-9-low-power-mode-benchmark-iphone-6Image Source: MacRumors

In regular mode, the iPhone 6 scored 1606/2891 for single-core/multi-core performance. Once Low Power mode is activated, Geekbench will register a much lower performance scores: 1019/1751.

The same goes for the iPhone 5s, which registered 1386/2511 in regular mode and 816/1405 in Low Power mode.

A yellow battery icon indicates that Low Power mode is active on a phone in iOS 9. To activate it at any time, simply go to Settings, then Battery, and you’ll see a toggle for Low Power mode at the top. Additionally, a Low Power prompt will hit your screen every time the iPhone has just 10% or 20% charge left, offering you the option to activate it.