Does this happen on other apps too?
I had a similar problem on my S3. Took ages to figure out what it was.
Turned out I had removed the memory card from my S2, put it straight into my S3 and there was some corrupt files on the memory card.
Reformatted the memory card inside my S3 and the problem disappeared. Phone was a lot quicker too.
Not sure why this worked but maybe worth a try. Backup your data on the card first of course.