With the launch of the new Android 4.4 comes a load of features which Google has released. Some of them include full support for 512 MB Ram phones and restriction free NFC enabled Google wallet. One of the more technical and important feature which Google enabled is an experimental 'ART', known as Android run-time. The prime reason why applications on Android run slower is basically because of them being run in a virtual environment.
Secret Experimental Android Run-time Speeds Up Application Execution
While iOS opens up application directly, Android runs them in a virtual environment using dalvik however this allows applications to be used on a variety of processors. Google has come up with a speeding up this process. Android employs 'JIT', known as Just in time compiler, this reads a partial code of an application everytime. By employing 'AOT' known as ahead of time compilation the code will be precompiled, applications will be opened up quicker than before. AOT saves a lot of time, however only application startups will be influenced most.
There are some downfalls to this also, a lot of time will be needed for ART to optimize your phone the first time u enable it, it will try to compile the code before hand and store it on your device, this will speed up the startup process but will take up some space. If u switch from JIT to ART and our phone has a lot of apps, ART will proceed with the optimizations at a snails pace.
This is a God send from Google, time and time again android was let down because of its virtual dalvik machine. This time around Google has done well to better the Android experience from the inside out.