Ios 7.1 On Iphone 4 Performance.

Specifically why can't iPhone 4 get past iOS 7.1.2?

First, let's dispel a common theory about Apple products: there is no planned obsolesce. Apple doesn't build its products and then specifically limit their capabilities so you will buy a newer model. Apple's philosophical DNA simply doesn't allow for this. Apple builds their products to last, and last, and last.There is no one real reason why an iPhone 4 can't get past iOS 7.1.2. There are several:CPU speed. Some of the features Apple introduces requires some pretty fast computational power. At some point the decision has to be made the performance of those features is unacceptably slow below a certain threshold.Hardware incompatibilities. Sometimes the hardware of an older product is simply incompatible. For instance, newer versions of the iOS look for the secure enclave that empowers the security of the Home button's touch sensor. Yes, they could bypass that. But bypassing functionality requires code, too. The iOS has to determine on what model it is running and then further determine which routines need to be skipped. Running those "determination" routines take time (see #1 above).User experience. When Apple determines the user experience suffers, they draw the line. Simple as that. When things slow down to an unacceptable level, it is time to discontinue support for that device in future versions of the OS (see #1 and #2 above). Developers. People who write software hate having to compensate for different methods used by different devices. The more unified the code can be, the fewer bugs with which they will have to contend. Cost efficiencies. It costs money to continue support for older hardware. Maintaining all the various versions, and tracking different results under different versions of the operating system is hard enough. At some point, you simply have to draw the line here, too.

Is it good to downgrade my iPhone 4 with iOS 7.1.2 to 6.1.3?

why ? because you can or u miss the old 6.1.3 , its not easy to downgrade and its not something you can do in an hour or so , quite simply its not worth the time and effort it takes to downgrade, u need a lot of things in place and you need to read a lot of things online and sometimes the downgrade fails and u will be left with a paperweight.if u have a perfectly working phone albeit a bit slow , try keeping minimal apps and keep using it.I personally tried to downgrade and wasted a whole lot of time and energy and ended up with a brick in my hand , somehow after spending a week online and numerous youtube videos and numerous posts i got it back to working condition.. so if u have nothing important on your hands to do u can Try to downgrade .lemme know how it goes and in case u need any help .. but its simply not worth it