GUI responses at different time on different computer

I have written a simple GUI, mainly contains three tasks: Capture images from a webcam, Display images, Do calculations.

I use the classdef to realize the GUI, and employ addlistener to listen events (update image, do calculations). The structure is simple: when I get one image from camera, the gui will notify an event to update the image, and do calculations. The procedure loops.

The problem is that: when I run my code on one computer (CPU @3.6GHz), it runs really fast without any delay. The response to all the buttons on GUI is immediately. However when run the code on the other computer (CPU @2.6GHz), the response is very very slow. The codes are exactly the same.

Could anyone help me point out what's the reason? I checked the profiler, the only difference is that each loop costs different time (0.02s VS 0.04s on different computer). But this cannot explain why the GUI response is so slow.