@Junkers
If you have issues with lag, make sure you don't have unwated garbage running in background, check apps, delete nonsense
and as last alternative you could simply root it then overclock your phone, it's not risky, you can get as much as 25% extra performance without any risk of damaging your hardware, and you can even setup profiles so that it will underclock the CPU automatically if the phone gets too hot
I use Samsung Galaxy SII and it works amazingly well