performance problems with writeDigitalPin function

Hi, i want to use my raspberry pi to control a stepper motor with matlab. Therefore i wrote a loop to control the pins ( with function: writeDigitalPins(...) )

My problem is, that this function really slows my loop down (to slow to get the needed frequency). I tried the same code as a standalone version with Python, where the performance was much better. So i am pretty sure the reason must be the write-function of matlab.

Does anyone knows how i can improve the performance? Thanks in advance.

The time (for one iteration) with 'writeDigitalPin()' = 2.6 seconds The time without : 0.5 seconds

The loop:

 seq =  [1 0 0 1;
         1 1 0 0;
         0 1 1 0;
         0 0 1 1];

 for i =1:1:1
     for i2 = 1:1:4
        writeDigitalPin(mypi,14,seq(i2,1))
        writeDigitalPin(mypi,15,seq(i2,2))
        writeDigitalPin(mypi,18,seq(i2,3))
        writeDigitalPin(mypi,23,seq(i2,4))
     end
 end