Hello, I am the one who did the scripting for Kohana. The amount of special effects (like rain, fire etc) might contribute on the lag on certain scenes (although I build Kohana on low end laptop myself- old i3 processors, 4GB RAM and no dedicated graphic cards). If your laptop spec is less than that then it might be the cause, but we are really sorry for the inconvenience
Oh yes as I said my specs is "very low", I also didn't have dedicated graphics, but I have 8 GB of RAM; though it's just RAM. I have Mobility Radeon HD 3400 as intergrated which is pretty bad itself and core 2 duo p8700 which have the same or a bit better specs than the i3 (three digit number) series~