It's surely related to the ridiculous SGS3 ram.
How many apps you have installed? Who are the heaviest ones (e.g. eventual tweaker, system monitor, optimizator, battery saver)?
From Boeffla Config you have to enable z-ram (if you didn't it) and choose 4 devices (one for each cpu core) for better performance.
If you continue to have similar issues with heavy apps/games try to increase the z-ram size (note that first you have to disable it and wait nearly 1 minute, until the action is completed).
Be careful to not exceed, ram under "that" size will be compressed as happens for zipped files, so worst performance due to overload and more battery drain.
For hopeless users no more than 300-400 MB, for normal users no more than 200 MB