MATLAB running same code slower and slower

I've no idea what's the problem. I ran this routine I wrote yesterday and it took 7 seconds, pretty much normal. Last night, the same routine took 30 secs. I tried restarting my com, reopening matlab, shut com down completely. Doesnt change. Today I tried it again and now the same routine takes 45 secs! Any idea or clue as what might be causing this?

By the way, is it normal for the program to utilize only one core? I've got an i7 but I'm not sure if matlab used to use all of them running this routine or not. But now it's using only one core.

Thanks so much in advance!

[Andreas Goser]

The question is if the code remains the same, but what is with the data? Same data? Appending data? Larger data sets to import?

[Jan]

Does your code append text to a log file, which is growing from call to call? Does the profiler show, where the additional time is spent? without seeing the code, we can only guess boldly.