Q: "My new Moto X Pure Edition/Style web browsing is REALLY SLOW on Android 6.0 ("Marshmallow") and I have no idea why (particularly with Chrome). What's wrong?"
A: It is because you enabled full disk encryption (FDE). The good news is that you can disable FDE. The bad news is that the only way to do it is to do a factory reset of your device, which will wipe out your phone and you will be starting again from scratch.
The reason why your browsing is slow is that the mobile web browsers cache pages to the storage on your smartphone. For some reason, one that I have not been able to determine, the Moto X Pure Edition (MXPE) doesn't seem to have crypto acceleration or it is implemented poorly, so the cryptography needed to support FDE significantly slows down storage access. This isn't apparent with most applications ("apps") because they don't do the same kind of storage access that a browser does.
There is only one way to accomplish the factory reset that will disable FDE on your MXPE (Disclaimer: I take no responsibility for you losing your data or the use of your phone):
- Make sure that you have been backing-up your device to the Google. If you haven't, you probably want to do that. I thought I was, but I wasn't, and still can't figure out what I did wrong. The place to look is Settings -> Accounts -> Google. Since this didn't do anything for me, please assume after you do this reset all your settings, apps, and data will be gone. They were for me.
- Back-up ALL the personal data you stored on the device to your personal computer. I CANNOT STRESS THIS ENOUGH! DO IT NOW! Get your photos, videos, music, and all that stuff off the device.
- If you haven't backed-up and saved your personal information listed in #2, you're not listening to me, and you should do it right now, because you're about to lose all of it. Seriously.
- I recommend that you disable any network access (WiFi or carrier Internet) from here forward. This will prevent your phone from being able to contact Google and potentially sync an empty phone.
- Write down a list of all the apps you have installed and any settings you think you may forget later. You will want to do this so you can install everything again later.
- If you have set-up your SD-Card to be additional internal storage, set it back to Personal Storage.
- Power off your phone and remove any SD-Cards or SIM cards in the phone. This is to prevent any part of the factory reset from possibly affecting these. It is probably not mandatory, but I like to be safe.
- Power-on the phone and go to Settings -> Backup & Reset and select "Factory data reset."
- Wait a while. The phone should eventually reset and power-on as though you just received it from the factory. Verify through Settings -> Security that under "Encryption" it says "Encrypt phone" (meaning that your phone is not encrypted).
Do not encrypt your phone's storage again. While this is a nice security feature, it makes the device virtually unusable.
After doing the factory data reset, the browsing using Chrome was very fast again, just like when I first got my phone. I came upon this after reading the testimonials from many confused people on the web who were having problems with their MXPE browsing being really slow and not knowing why. I started thinking what I did that led to it being slow, and when I enabled encryption (FDE) was when it started.
Not using FDE is not generally going to put your data at risk. It's good for protecting your data from someone who has physical access to your device from being able to reset it and gain access to the data in the storage. If you're really worried about someone getting access to your lost device, there are ways to remotely wipe the device if it is lost. If you're worried about government access to your device, then the MXPE is probably not the right phone for you.
Hopefully this helps someone avoid the frustration that I and so many others seem to have been experiencing.
A note about SD-Card storage:
While you're wiping out your phone, you should probably think about your SD-Card storage with Android Marshmallow. While it is possible to use the SD-Card as extra "internal storage," I don't recommend doing this. Using the SD-Card as internal storage makes your entire device dependent upon keeping the SD-Card in the device. If you remove it, you can end up with lost data or corrupted settings. The only time it makes sense to use the SD-Card as internal storage is if you cheaped-out and ordered the 16 GB model and now are tight on space for apps and games. If you're a typical user and have a 32 GB or 64 GB model, then you've got plenty of app/game storage.
Instead, format the SD-Card as "Portable storage." This will still allow you to keep music, movies, and photos on your SD-Card. You can take the SD-Card out of your phone and access it on your computer if you need to do that. If the SD-Card goes bad for some reason, you won't start having problems with the rest of the phone (you'll just lose your media, which you should be backing-up anyway).
It seems like a good idea to extend your internal storage, but everything I've read online and experienced personally after trying it says not to do it.