[Xperia Tablet Z General] najoor:
** DISCLAIMER: I AM NOT A DEVELOPER. I DO THIS AS A HOBBY AND SHARE MY FINDINGS IN CASE SOMEONE ELSE FINDS THEM USEFUL. **

** THIS WORKED ON MY DEVICE BUT IT MAY NOT WORK ON YOURS. APPLY AT YOUR OWN RISK **​

Background:

Tablet Z is an amazing device. I have had a number of different Android devices with comparable specs but nothing has come close to this one in overall performance, durability, build, and stability. The question that I did not find an answer for and made me write this info piece is: what is the best stock ROM for this tablet that can offer the best overall stability and power consumption. Note that a lot of what follows are matters of opinion and personal preferences and you should probably tweak based on your specific needs. So first some basics.

Basics:

There is an empirical finding that the best performance is achieved from the ROMs that are available about six months to a year after the release of any given device and here is the justification. The device is initially shipped with the Android version available at the time of the release. This initial version is invariably buggy because the fast design cycles of these things do not allow a comprehensive test drive by the vendor. So the consumers report the bugs, they get patched, and about 6 months later everything is wrapped into the next version of Android and pushed as an update. This second ROM release is much more stable than the first one but still lacking a few things here and there, which brings us to the next major ROM that will fix most everything.

By this time we are 6 months to a year into the life of the product and the market is now seeing other devices with higher processing power and better specs. The Android releases at any given point in time are tweaked towards the expected performance of the devices that are available at that time. So the next update for your now-more-than-a-year-old device will have nicer features but it is geared towards other devices that are faster and better than yours. So now you upgrade to the third release and you will find that while all the initial bugs are gone the device is laggy and the battery goes down faster than it used to. Most devices don't have a straightforward procedure to downgrade to an older version (at least for the common user) and therefore you will just write this off as your device being too old and slow and then you will be likely convinced by a Sony salesperson to buy the next generation tablet and that is the end of that.

The key is to identify that sweet spot where the OS is stable and fast and tweak the performance there and NOT upgrade anymore. Let me say something about software upgrade while I have your attention. I have sadly found that a lot of people upgrade their phone/tablet OS without really knowing why they do it. Sometimes it almost looks like a fashion trend that since my neighbor is running his/her phone on Kitkat I must upgrade from Jellybean too. This often results in a slowdown of your system and sometimes even makes it impossible to do cool stuff such as rooting your device, because new updates close loopholes and vulnerabilities.

Xperia Tablet Z Stock Roms:

Before we get into that, let's mention the non-stock Roms such as AOSP and CM and their derivatives. There may be a compelling argument for certain cases where for example the vendor either heavily loads the device with bloatware that is difficult to remove or a custom Rom is needed to improve power or increase the performance by overclocking and whatnot. This is very true of some Samsung models with great hardware that are actually degenerated to slow devices with over-bloating and a little help from possessive phone operators like AT&T. However, this is not particularly true for Sony, or at least not yet. The Sony bloat is minimal and easy to remove and what Sony packs with the OS, such as multi-window, remote control, and Bravia engine, are in fact quite useful especially if you are using the device in a Sony ecosystem like with a big screen TV. Besides, Sony is very open-source friendly so there are not a whole lot of locked down features that you may need a custom ROM to get around. So I will limit this discussion to Sony's official Rom releases.

XTZ was initially shipped with 10.1.C.0.344 Android 4.1.2 in the US. Within a few months they upgraded it and if you like most people bought your tablet in the summer of 2013 it probably came with 10.1.C.0.370. This was to fix a touch sensitivity problem and improve WiFi. No update however is complete without limiting the ability of the user to root the device so Sony patched a vulnerability that allows the method of rooting you find inside the menus of Flashtool. Soon another vulnerability was discovered and a piece of code was written by Doomslord which would remain the only safe way to root XTZ until Towelroot was born. The update also removed the ability to choose the number of active cores, which was not the end of the world of course.

This release arguably has the best user interface which located the important touch keys on the bottom left and right sides of the screen, which is easy to operate when you grab the tablet with two hands. However, it had a few performance issues. For example, adding a weather widget would introduce a visible lag when swiping the home screen. It didn;t take long before users started nagging on different forums about how they are not running the latest Android version and how Sony should release it ASAP,... and Sony did.

Android 4.2.2 (10.3.1.C.0.136) removed the nice tablet UI. Soft button keys were now at the bottom center of the display with nothing on the left and right sides, which makes it awkward to grab the tablet with two hands and operate these keys at the same time. The notification area that was previously on the bottom right hand side would now be relocated to the top banner which resulted in a loss of screen real estate, and this pissed off a lot of users including yours truly. In all fairness it was not Sony's fault because this was a decision made by Google to unify tablet and phone interfaces beyond 4.2.2. Sony did their best to give something back (Quick Settings option in top notification bar) and mitigate the lost screen area (Semi-transparent bar in lockscreen). Then there were added features like multi-user support, ability to change the length of “preview time” after shooting a snap from camera, widgets on both homescreen and lockscreen,Video Unlimited movie app integration, updated media apps, my Xperia app to track the tablet in case it is lost, and official support 64 GB SD card.

The initial 4.3 release (10.4.B.0.577) changed the UI to a white theme that looks a lot like Xperia Z1 and Z Ultra: new improved smart camera app and new Xperia wallpapers (like Xperia Z1). A cool feature was added that allows the downloading of themes which change the navigation bar and status bar colors, and the soft keys icons as well. New keyboard app was added with one-hand keyboard settings. Also, a Windows Tethering option made it possible to pair the tablet with Windows 8.1. All welcome options which made most of us get over the grudge caused by the removal of the Tablet UI. Screen was calibrated for a brighter display and restricted profiles settings added more control of the multi-user feature.

The best feature which went unnoticed by many was the new version of Battery STAMINA Mode. Not that the older one needed any serious make-over but this one offered even a longer battery life. By now, almost all the lag observed in earlier versions were gone. For example, the weather widget would no longer self-update until the swiping was complete and this provided a significant smoothness in home display transitions. Finally, the 4.3 update 10.4.1.B.0.109 reduced the display flickering, improved battery life, shortened shutdown times, and fixed a problem which made it possible to use Bluetooth without losing WiFi.

Sometime in May of 2014 Sony released the long-awaited 4.4.2 Kitkat update (10.5.A.0.230) and this was when things started to go south. Sure, there where enhancements in camera app, ability to add emojis to messages, screenshots via the power menu, updates to Email, Calendar, and other apps, and good looking live wallpapers. But nothing could hide the fact that the tablet was now visibly slower and the battery would drain much faster. Sony admitted that the battery drain is a real problem and traced it to a buggy version of the Google services, which the user could uninstall or disable but that didn't make the update any faster.

The fact is, Xperia Tablet Z has a snapdragon S4 running at 1.5GHz, which from an antutu score perspective sets it at around the 20-21k mark. For comparison consider the Tablet Z2 with a 2.3GHz Snapdragon 801 with an antutu score in the 35000 range and that is really the type of system that the Sony Kitkat update should run on. That's why the tablet becomes so sluggish after the kitkat upgrade. The transitions are visibly slow and even if you disable live wallpapers and other things the settings menus will remain slow. In fact the antutu score after this upgrade drops sharply to around 18000.

Sony eventually released Kitkat 4.4.4 with 10.5.1.A.0.283 in late summer of 2014 and updated that a month or two later with a limited release of 10.5.1.A.0.292 in Nordic countries. These update are more fluid than 4.4.2 with much less lag in different programs. All Kitkat releases have been plagued by a sever battery drain due to a malfunctioning of Google Play services, which is resolved if you update this app to 5.2.08 after the firmware installation. 4.4.4 is still slower in Antutu scores compared to 4.3.

And the winner is...

4.4.4, followed by 4.3.

With the latest Kitkat update (4.4.4) I found that after patching the Google services and minimal debloating the tablet will last 78 days (more than two and half months) in standby. That is pretty impressive. See the screenshots (under Attached Thumbnails). So if you decide to go with 4.4.4, to get the most out of your battery:

1- Upgrade Google Play services to 5.2.08.

2- Go to settings:

Wifi -> Advanced -> Keep Wi-Fi on during sleep -> Never

Wifi -> Advanced -> Scanning always available -> off

Wifi -> Advanced -> Wifi optimization -> on

Power management -> Stamina Mode on and queue background data

3- Disable Google+ and Hangouts (and play store, if you don't use it). I suggest turning off both "Remotely locate" and "allow remote lock" options under Android device manager in Google settings.

4- Uninstall (via Titanium backup) or remove from /system/app and priv-app SonyEntrance.apk and UpdateCenter.apk. If your tablet is wifi only do the same for SemcTelephonyProvider.apk, Stk.apk, phone-usage.apk, and SemcPhone.apk.

The 4.3 update 10.4.1.B.0.109 provides a good battery life too. In standby it can last about 55 days without a recharge (see 1.jpg and 2.jpg). In camparision, the 4.4.2 release lasts about 40-45 days under similar testing conditions. To install 4.3 you can either use this long procedure: http://xdaforums.com/showthread.php?t=2772943 which gives you a pre-rooted 4.3, with the added benefit of a nice recovery image, or flash a stock ftf and root it with towelroot. Either way you need to learn and use flashtool because this update is no longer available through Sony's update channels. If you decide to go with 4.4.4, to get the most out of your battery:

1- Root and disable non essential programs either using Titanium backup or other methods that require a knowledge of the terminal emulator. On an SGP311 For 4.3 what you typically disable is the following (the list is different for the LTE version!):

B2bCustInstaller, com.sonyericsson.startupflagservice, Crackle, Facebook, FBiX Post Viewer, Gmail (and use the stock Email client if you have want to check your gmail), Google Play Books/Games/Magazines/Movies/Music, Google+ and Hangout, Let's start PSM, McAfee Security, Mobile Data, Mobile Network, Configuration, Netflix, POBox Touch (unless you use Japanese keyboard), Reader, Sim Lock, Sim Toolkit, Social Engine, Socialife, Twitter, Video Unlimited, Wisepilot (which doesn't work anyway!), Xperia AppShare, Xperia Calendar Sync, Xperia Friends' music, Xperia Music Likes, Xperia Social Engine Photos/Sharing (all of them), Xperia Chinese keyboard, Xperia with Facebook and Twitter.

2- Then go to settings:

Wifi -> Advanced -> Keep Wi-Fi on during sleep -> Never

Power management -> Stamina Mode on.

I tried programs like Juice Defender but it seemed that in the presence of Sony's Stamina mode none of that is necessary.

One last detail. As you can see in the picture mobile data is still burning 3% although I froze/disabled it in Titanium. The reason is that while freezing an app prevents it from starting at boot-up, the binary is still in the storage and other apps can still invoke it. If you want that portion to go down to zero you will need to uninstall the app in Titanium (or delete/rename the app to disable it, which requires knowledge of the terminal emulator.)

Update: Sony released 5.0.2 with 10.6.A.0.454 in late spring of 2015 and 5.1.1 in September. The standby battery life is nowhere near the latest 4.4.4 or 4.3.

So that is it folks. Give it a try and see it for yourself. At the end of the day, regardless of the firmware, this is an awesome tablet which will still be around after all of its peers are gone and forgotten.