iPhone 15 Pro Max performance issues after iOS 26 update with Apple Intelligence enabled

There may be several reasons why an iPhone may behave as described by you.

Let's delve a bit deeper into some of them:

1. Storage: A full iPhone can definitely slow things down. Phones can experience performance issues when the storage is nearly full. Users can check their storage status by going to Settings > General > [Device] Storage. Deleting unnecessary apps, photos, or videos can free up space and improve performance. How to check the storage on your iPhone and iPad - Apple Support.
2. Battery Health: A degraded battery can impact performance. A deteriorating battery can impact the overall performance of an iPhone. Checking the battery health can be done by going to Settings > Battery > Battery Health. If the maximum capacity is significantly reduced, it might be time to replace the battery. Prolong and Maximise Battery Performance … - Apple Community
3. Incorrect Handling: Accidental drops or bumps can cause internal damage. looking at the Apple's guide on proper handling is a good step. Important handling information for iPhone - Apple Support (IN)
4. Environmental Issues: Extreme temperatures, dust, and water exposure can all be detrimental.
   1. Keeping iPhone clean is an important step. Dust accumulation in the iPhone's ports and openings can affect functionality. Apple provides guidelines on how to clean iPhones safely, which usually involves using a soft, lint-free cloth to remove dust without causing damage. Cleaning your iPhone - Apple Support
   2. Keep the iPhone within temperature limits. Phones are designed to operate within a specific temperature range. Exposure to extreme temperatures, especially in parked cars, can lead to overheating or other performance issues. If your iPhone or iPad gets too hot or too cold - Apple Support.
   3. Addressing safety issues is also important: Important safety information for iPhone - Apple Support (IN)
5. Unauthorized Service: Servicing an iPhone through unauthorized channels can result in substandard repairs and void warranties. Users should always seek authorized Apple service centers for repairs and maintenance.
   1. Repairs by unqualified technicians can introduce new problems. Find information about your warranty or AppleCare plan - Apple Support is helpful.
   2. Modification / Alteration of an iPhone by a third-party vendor may cause issues beyond repair. --> Unauthorized modification of iOS - Apple Support (IN)
6. Jailbreak: Now, let's talk about jailbreaking. Jailbreaking removes Apple's restrictions, allowing for more customization and app installation outside the App Store. However, it can also lead to instability, security vulnerabilities, and issues receiving future iOS updates.

By considering all these possibilities, you've provided a comprehensive approach to troubleshooting the iPhone's behavior.

Understanding and addressing these factors can help you maintain the optimal performance and longevity of their iPhones. Following Apple's guidelines and seeking authorized support when needed are crucial for a positive user experience.

If you are sure it is the fault of the equipment.

If you have either dropped the device accidentally or exposed it to liquid or used it beyond acceptable temperature limits then…

Take your device to an Apple Retail Store or Apple Authorized Service Provider, or contact Apple Support:

Find Locations - Location Selector - Apple

Contact Apple for support and service - Apple Support 

Get a Genius Bar Reservation and Apple Support Options - Apple

Contact Genius Bar.

Manage Reservations - My Reservations - Apple

iOS performance issues are not always the iOS update's fault!  Many things can cause phone problems.  If you tell people you think it's an iOS update, it might make it harder to fix or find a solution for the real issue.

Remember, the right question often leads to the solution!

Was/Is your device Jailbroken? If that's the situation, please be informed that attributing the issues to iOS updates may not be accurate.

iOS updates aim to enhance user experience, boost security, and fix bugs rather than disrupt core features. The majority of the issues after updates might stem from underlying, unmentioned factors. Updates won't typically alter personal data but may refine settings or features. Backup before major updates for safety. Review Apple's update details and backup advice for a smooth process.

Kindly consider checking your settings and addressing any device issues before attributing the issue to external factors. This could be a pure coincidence that the iOS update affected the iPhone functions.

Before initiating a standard iOS update, it's advisable to create a backup. Have you completed this step? If yes, proceed with the restoration from the backup.

See what each update does: OS — iOS 26, About iOS 18 Updates, About iOS 17 Updates, About iOS 16 Updates, About iOS 15 Updates, About iOS 14 Updates, About iOS 13 Updates, About iOS 12 Updates, and so on...

clay_nprsut wrote:

Random apps just become unresponsive,

Delete the app, then re-download it  Then redownload the app. Then check whether the problem with the app is fixed.Read more

If an app on your iPhone or iPad stops responding, closes ...

clay_nprsut wrote:

and autocorrect has a mind of its own now.

Choose the correct language where the name is used correclty.

Add a keyboard of the desired language, and if the language is supported for dictation, then dictation language is automatically added under Settings > General > > Keyboard > Dictation Language

There isn't a strict language division between "Charli" and "Charlie." Both spellings are primarily used in English.

• Charlie: This is the more common spelling, traditionally used as a masculine name or a nickname for Charles. However, it's becoming increasingly popular as a unisex name.
• Charli: This is a less common variation, often seen as a more feminine or creative spelling of "Charlie." It can also be a nickname for Charlotte or Charlene.

While some sources suggest a German origin for "Charli," it's not widely recognized and both spellings are considered part of the English language.

clay_nprsut wrote:

....and now I just can’t seem to find a good reason to stay in the Apple ecosystem.

Mobile brand/model selection is an individual choice based on many parameters. Such as Money, Feature, Status, Aesthetic, Utility, User-Friendliness, Availability, Warranty Coverage, Service Support, Resale value, Technology and many other factors. Choose yours judiciously!

clay_nprsut wrote:

Does anyone else notice a lack of quality or performance in device use since the 26+ updates?

I have no such issue on my iPhone 13 Pro and iPhone 17 after updating iOS 26.3