Extremely Slow Script Execution with New Laptop

Hi Everyone,

A colleague and I are working on a dynamic optimization routine that requires the use of rather large arrays and a good number of nested for loops (vectorized what I could). When my colleague runs the program on his 6-year-old university computer it executes in roughly 40 seconds. When I run the identical code on my new i7 laptop, it takes roughly 22 minutes. We also tested it on a two-year-old machine, which took about 30 minutes to run.

I'm sure there a ways that the code could be more optimized than it is now, but I'm rather perplexed at the time difference in spite of that. Unfortunately, the i7 is the only computer to which I have access and I need to up the discretization level - bumping the run-time up to about 2 hours ... sort of tough to check logic with that.

I've read the discussions about how MatLab doesn't use all available cores and so on, and the resource monitor shows the expected 25% processor load. It doesn't seem like this should be much of a factor considering the age of the other machine...

If anyone has some insight into this, I'd really appreciate it.

Thank you!

[Walter Roberson]

Interestingly, someone recently posted a quite similar question, except for i5

http://www.mathworks.com/matlabcentral/answers/28753-the-same-matlab-2009a-much-slower-in-windows-7-64bit-i5-2410m-than-xp-32bit-core-2-duo-computers

Answer 1

[Matthew]

Hi Sean,

I experienced something virtually identical running a program with a bunch of ugly nested loops. Specifically I had ~17x slow down when I went from a four-year-old dual 32bit dual core XP windows machine to a new 64bit quad core i7. I originally thought it might be the new version of matlab that was the problem (I had R2009a on the older machine, and put 2011a on the new machine), but when I downloaded and ran the 2009a version on the 64bit machine I had the same slow-down. I therefore figured it had something to do with the difference between the 32bit and 64bit versions. Long story short, I installed a 32bit version of the 2011a on my new machine, and when I ran the 32bit version, the program screamed (instead of being 17x slower, it was 3x faster than my old dual core machine). So although this exactly address the problem, it offers one potential brute-force fix that might work for you as well. Good luck, Matt

[Daniel Shub]

I hope you reported this to TMW technical support. These are the types of issues that they need to know about.