If you are using custom Android 4.4KitKat ROMs such as CyanogenMod, Paranoid Android or AOKP that ships without Google Apps package then you should install a GApps package to get all Google features after installing the ROM. However, if you really wish to use ART runtime instead of the Dalvik, you should also use ART compatible Google Apps package.
Paranoid Android team has released ART compatible Google Apps (Gapps) package that should work fine on any custom Android 4.4 and above ROMs to help you mitigate core Google application compatibility issues when switching to ART. Features of PA’s ART compatible GApps package You can download the ‘0-day initiative’ ART compatible Google Apps package from source here. Now, if you don’t know how to switch to ART, read my previous article. It is quite simple – Go to Settings>Developer options, tap Select Runtime and choose Use ART. Click OK to confirm. After rebooting, it will display a message informing you that “Android is upgrading”. Once Android starts, your phone should be much faster!