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I used GeekBench 3 to test the update before and after upgrading both of my devices. Both my iPad 2 and iPhone 6 showed slightly better performance after upgrading. As you can see, the iOS 8.4 upgrade actually has a higher multi-core score on my iPad 2.
GeekBench only tests algorithms, not the actual performance of apps. It was unable to discover the serious flaw rendering Apple Music and other apps useless on older devices. Once again, Apple has improved the lower-level aspects of their operating system, only to have serious flaws introduced by their application team. My hunch is that the Safari team is responsible for the embedded browser (UIWebView, DLWebView), which is used by several apps.
Installing iOS 8.4
The iOS 8.4 upgrade time varies based on your device and how often you upgrade. If you have been updating your device regularly, the update will be between 78 – 218 MB. The update was 78.5 MB on my iPad 2 and 218 MB on my iPhone 6. If you have been updating regularly and you have a decent Internet connection, the update should take 30-45 minutes.
After the update, expect your device to be a little slow. The battery will also drain faster. This is because a post-upgrade optimization process is being run. With Apple Music, your device will be doing some additional processing to analyze your musical preferences, integrate your iTunes purchases and sync with iCloud. As usual, people are complaining about this right away. Wait a few days before you start screaming bloody murder on social media.
I waited a month before writing this article. I feel it is necessary to actually use 8.4 before writing about it. After a few days, iOS 8.4 will not detract from performance or battery life on a new device. Keep in mind, if you are using Apple Music for several hours and streaming music, it will drain the battery faster than surfing the web or other activities. People will often play music over AirPlay while browsing for other music. The iCloud Music Library may be doing some syncing activity. Apple Music server components may be communicating with the client to provide recommendations. One should expect this to use a significant amount of battery power.
WiFried Bug Reintroduced in 8.4
Although I have not personally experienced this issue, several users are complaining that the so-called “WiFried” defect has resurfaced. The bug can disconnect or slow WiFi. Apple fixed WiFried in iOS 8.3. If you experienced this bug and it was fixed in 8.3, I strongly recommend holding off on iOS 8.4.
If you have persistent WiFi issues, please read “Fix iPhone WiFi“. This guide provides information on fixing iPhone WiFi problems and tuning your WiFi router to avoid frequency collision. The WiFried bug may be exacerbated by frequency collision with your WiFi network. Other wireless devices (cordless phone, audio transmitter, baby monitor) or your neighbor’s WiFi network could be interfering with your WiFi router’s signal strength. I improved WiFi performance by properly configuring the WiFi channels on my AirPort Extreme router.
Other Bugs Introduced in iOS 8.4
Apple Music introduces quite a few issues in iOS 8.4. Adding music from the For You screen to a playlist doesn’t work most of the time. I can’t get it to work at all on both of my devices. You can workaround this problem by tapping the “…” button next to a song or album and choosing “Make Available Offline”. This will download the music to your device. Tap on the My Music tab at the bottom of the screen to access your downloaded music. Adding downloaded music to a playlist works. (continue…)