When you get your Nexus 5, you can drastically speed up your apps with Android's new virtual machine in 4.4. They are calling it Android Runtime (ART) and it's replacing the old Dalvik runtime.
Summary: Go to Settings->Developer options to change runtimes. With ART, apps may be up to twice as fast because it uses the Ahead-Of-Time (AOT) compiler rather than Just-In-Time (JIT) compiler.
More info: http://www.androidpolice.com/2013/11/06/meet-art-part-1-the-new-super-fast-android-runtime-google-has-been-working-on-in-secret-for-over-2-years-debuts-in-kitkat/