Google Play Music App Unresponsive or Slow

I reverted my Moto G (2013) to the stock ROM and rooted it, but since I did this, I have been having frustrating problems with Play Music that make it unusable:

• Select a song and nothing happens 
• Press play and nothing happens 
• After several minutes a song may play, but pressing pause won't stop it

Killing the running Music app will obviously get a playing song to stop, but the base problem is still there -- the entire app is basically useless.

I tried wiping data for the app, wiping the app's cache, rebooting the phone... nothing helped, and Play Music remained a slug.

SOLUTION:
Today I completely uninstalled the app using Titanium Backup.  Since Google Play Music is a system app, you will need root privileges to do this.

After completely uninstalling the system version of the app from the phone, I re-installed it through the Play Store, and so far it behaves as I expect it to.  Something must be incompatible between the factory version and the "update", however that mechanism (system app vs. "updated" version from market) works in Android.

Update 28-Feb-2015:
This started happening again.  I removed Play Music and re-installed it, and it started behaving again.  It might be due to having a lot of cached music on the phone, I don't know, but it is annoying the hell out of me and I am going to install CyanogenMod again tonight to see if it is a problem with the stock ROM.