Was exited to see Sony's blog post about updating all the 2011 Xperia smart phones to Ice Cream Sandwich? Well, the company itself has issued a warning blog post explaining how ICS differs from Gingerbread when it comes to performance and usability on relatively older hardwares (2011 Xperia Smart phones). The company won't be notifying you about the update, neither will they provide OTA update to ICS is a clear proof that Sony is not interested with their 2011 Xperia users updating to ICS.
Sony advises that it's not a bad decision to stay with Gingerbread as ICS is more intensive in terms of memory management and it requires more RAM and CPU to work flawlessly. Sony says that ICS was developed targeting a phone with a Dual core processor supported by 1GB RAM but sadly, all the 2011 Xperia smart phones run on a single core processor and a 512MB RAM. (It's a mystery why they are still releasing phones like Xperia U and Xperia sola. We have already discussed this in our forums.) 512MB is ideal for Gingerbread but when it comes to ICS, the apps use relatively higher memory; for example the web browser uses 20-30MB more in ICS compared to Gingerbread. This is the case with almost all the apps running on ICS and hence it'll be difficult for the 512MB ram to handle apps on ICS.
So when the phone runs out of memory (RAM), the activity manager will start to close processes according to priority. At first the background processes will be killed and lastly the foreground activity will be halted. The image below will give a clear idea of how android manages processes when it runs out of memory.
When running a memory intensive game, the background processes like dialer or the home screen app will be killed and later when the gaming session is over, the phone will seem to be laggy since all the closed processes needs a restart, which takes time and slows the system down. RAM shortage is the main problem in 2011 phones but they are also blaming slower interaction with the SQL database and hardware acceleration which can have negative effects on the user experience.
On the other hand, Sony also mentions the goodies of ICS; like the new holo theme, over a thousand modified icons, new wallpapers and application backgrounds, the activity manager with a completely new UI (swipe to close an activity), Face Unlock, new calender and contacts apps, visual voicemail etc.
So, it's the end user who is to decide whether to go with ICS so that you avial the cool new features mentioned above or to stay with Gingerbread and thereby enjoy a relatively stable ROM (on 2011 Xperias).
Fore more information on this and about all the technical aspects the differ ICS from Gingerbread, visit the Sony Blog.
Source : Developer World