WidgetLocker + Music controls

[Kahless]

Hi all. I've recently (few months) got my first ever android phone and I am loving it (previous Win7 and Nokia before that), as I find it easy to customise. I've come across a small problem I'm hoping someone will be able to help with.

First off my phone is a Samsung Galaxy S3 (GT-I9300), running un-rooted android version 4.1.2.

I've installed Widgetlocker (great app!) and wanted to put some music player / volume controls on the lock screen. I'm using the stock music player and the widget for that is okay. I downloaded Phantom Music Controls and made a simple 3 button widget with Previous, Play/Pause and Next. I placed the widget on my lockscreen and tried it out. however, when I press a button it lags for about 10 seconds before it changes track/pauses/resumes. I thought it might be a problem with PMC so I tried widgetsoid, but I have the exact same problem. The stock widget for the player works without lag and PC and widgetsoid both work fine on the homescreens.

Does anyone know how to solve this?

WL / PMC / Widgetsoid are all installed on my phone memory. Songs are stored on an SD card.

Thanks in advance!

Edit: Should mention that a flashlight widget I created using widgetsoid works without lag on from the lockscreen