I'm running highly inefficient MATLAB code which I wrote myself.
This code repeats the same calculations several times uselessly.
It will take several more hours to complete because of this.

No, I do not care; it is fine and I can wait.
I do not want to spend any more time adjusting code, specially in MATLAB; I already spent way too much time in the profiler to reduce memory consumption.
I just make sure to save progress any once in a while so that if something goes wrong I don't lose all the results.