MATLAB speed coding C++

My name is Riyadh Hanashmooni. I am PhD candidate in CSM, CO. I got MATLAB 2017b on my computer from the university. I wrote a code of simulation (Petroleum). My computer is HP_ i core 7, very high speed. I do not have any problem with speed. My code was working very fast. Suddenly, and without adding any new statement to my code, the run becomes too slow. I tried everything, cleaning, anti-virus. Then change some of the coding statements to get more speed, but I could not! Is there any suggestions because I can not able to work! Please advice. Please send the answer to my email [e-mail].

[James Tursa]

We need more details about your code. E.g., maybe you are running into a memory limitation and your program has suddenly started swapping out to disk.