How to fix iPhone 13/12 Calendar Lags and slow after iOS Update ?

Many iPhone 13,12 Pro max users are facing issue with the calendar app getting slow after iOS 15.1 update. The iPhone calendar is slow and it looks like it gets stuck and keeps on lagging while typing or setting a meeting. The issue is across all different models of iPhone including iPhone 6s, 7 plus, iPhone XS MAX, iPhone 13,12 Pro max etc.

iPhone 11 calendar slow/laggy 

The issue was not seen with earlier version of iOS 15 but after updating to iOS 15.1 the calendar on the iPhone lags a lot , slow to respond, scrolling is awful after iOS 15.1 update. Even on opening the calendar app , it shows black screen for few seconds and loads very slowly on the iPhone . Moreover the iPhone calendar app seems to be stuck and consuming too much battery. 

How to fix Calendar not working /slow/lagging/stuttering after iOS 15.1 on iPhone 6s,7,8,XR,XS MAX, iPhone 12/13 Pro Max : iOS 15

Fix : Change/Turn off Sync settings on Calendar

As the issue is not only calendar getting very slow on iPhone but also taking too much battery on iOS 15.1. Thus there are chances that the iPhone calendar is getting stuck on a task. To fix iPhone X,12 slow calendar app , change the sync settings of calendar app. Go to iPhone calendar account settings and check update is setting the sync option to all events. After switching to Events two weeks ago the calendar should work normally.

Fix : toggle Internet

A workaround to fix slow calendar issue is to toggle WIFI or mobile data on the iPhone. This way the calendar becomes more responsive. You may use it as workaround until the problem is really fixed. 

Fix : Reset network settings

To fix slow calendar app on iPhone 12,13 etc please try to reset the iPhone network settings. This will fix any network setting related glitches which may cause calendar issue. 

1. On iPhone, tap Settings > General > Reset.
2. Tap Reset Network Settings.
3. Type in the device password if prompted.
4. Confirm selection. 

Fix : Reset iPhone 

Due to some software glitch in the iPhone, the iCal app may not work properly. To fix that reset the iPhone, this will not erase any data but all setting will be lost. Go to iPhone settings->General->Reset of Transfer iPhone-> Reset Settings. 

Fix : Use third party apps 

Google calendar for iOS and iPad do a great job. If you are finding Apple calendar app difficult to use, you can always switch to the Third party apps for better experience. 

You will have to give permission to the Google Calendar app to read iPhone's local calendars, it displays the dates and times absolutely perfectly even if they are incorrect in the iOS Calendar app.

Source: Shudtech