Users may found their iDevices are running very slowing and constantly crashing. Here, you can know how to fix this problem.

NOTE: 

• This method has only been tested in iOS 9.3.2. Not sure about the feasibility on iOS 10 or later.

• DO NOT just go to settings and do a factory reset from there.

1. Removing All Tweaks

Before you do this, you might want to delete your tweak preferences, using an file manager and navigating to var/mobile/library/preferences to delete them. then, you will want to remove all of your current tweaks first by uninstalling 'Cydia Substrate' This will uninstall all of your current tweaks. But don't worry, it will be automatically installed when you re-install a new tweak.

If this fixed your constant crashing and slowing down, there is no need to continue unless you want to. Just re install your tweaks and you are good to go. Otherwise, continue to the next step.

2. Backing Up

After you remove Substrate, you will want to backup your device to iCloud as the following step will reset your device back to factory settings. The reason to backup your device after you have uninstalled Substrate is because that iCloud may save your tweaks.

3. Unjailbreaking W/O Updating

Go to Cydia and install Cydia Eraser. This will unjailbreak your iDevice and factory reset it. So it will basically be a brand new iDevice. The process might take a while, so please be patient. After the process is done, you will be greeted with the 'Hello' page just like a new iDevice. Be sure to restore your earlier backup if you would like your data and everything.

4. Re-Jailbreaking

Here, you need to re-jailbreak your iDevice on 3uTools. 

Congratulations! You should have Cydia re-installed onto your iDevice. Go install your Tweaks! There are many introductions of different kinds of tweaks in our "Tutorial" page, check and get the one you like.