Since the release of iOS 17.4, many iPhone 12 users have reported slowdowns, less rapid animations, or a battery that drains a bit faster. On forums and social networks, these reports have fueled the debate: is the phone really becoming less efficient after the update? Some talk about a feeling of slowness, others notice no difference. Faced with these contrasting testimonies, it is important to separate what is actually happening on the software and hardware level from what is subjective perception.
When we talk about performance, the first question is: are there tangible measurements before and after iOS 17.4? The first independent tests comparing the iPhone 12 under iOS 17.3 and iOS 17.4 indicate a slight difference in some raw performance indices, but no dramatic drop. For example, CPU scores may be 2 to 5% lower after the update, but remain within the same general power range.
This slight gap can be explained by the adjustments Apple makes in its system to optimize energy management or stability, rather than by an inability of the hardware to keep up. In other words, the iPhone 12 remains capable of delivering strong power, even after iOS 17.4.
So if the numbers don’t drop dramatically, how do we explain the feeling of slowness that some describe? Several elements contribute to this impression:
Rescheduling of system tasks
After a major update, iOS recalculates certain background process priorities. This can temporarily slow down the opening of applications or the execution of animations until the system has completed these adjustments.
Caches and internal indexing
As soon as iOS is installed, the device rebuilds internal databases (for example, for photos, messages, applications). Until these operations are completed, the iPhone may seem less responsive, even if it is not a lasting performance loss.
Third-party applications not yet optimized
The update changes internal APIs used by many applications. If some are not yet adjusted for iOS 17.4, their opening or execution may seem slower. This phenomenon does not reflect a decrease in the phone’s power, but a temporary lack of adaptation.
Alongside discussions about speed, many users are concerned about less battery life after iOS 17.4 on iPhone 12. Again, measurements show there is no steep drop. However, several phones show faster wear in the days following the update.
Why? Because iOS performs many background tasks right after installation: indexing, photo optimization, service refresh. These actions consume energy. Once this work is completed, battery life generally returns to a level close to that observed before the update.
Users note an improvement after 24 to 72 hours, which corresponds well to this post-installation adjustment period.
Even if iOS 17.4 does not cause a major power loss, it changes certain internal system structures. For example:
These changes can be felt differently depending on usage:
a user who relies on heavy applications may perceive a slight variation in opening time, while another who uses light tasks notices nothing at all.
Some users have reported truly annoying behaviors, such as:
• applications closing without warning,
• temporary screen blackouts,
• longer load times when launching native functions.
These cases remain minority. They can often be linked to specific installation issues, atypical usage profiles, or applications not yet adapted to the new iOS version.
Specialized labs that test smartphones before and after updates confirm one thing: iOS 17.4 has not caused a catastrophic drop in performance on the iPhone 12. The variations observed remain within a low and normal range for a major software update.
They also point out that Apple tends to prioritize stability, security, and longevity of the system, which can result in a redistribution of resources, sometimes perceived as a decrease in activity by the user.
If you feel that your iPhone 12 is less responsive or that the battery drains faster after iOS 17.4, several simple steps can help:
In most cases, these actions allow you to regain responsiveness more in line with what you knew before the update.