Matlab slow when running many instances?

Why does matlab become slow to respond when many instances are opening? I have two workstations, one has an overclocked i7 4960x (12 virtual threads) and the other is a 2x Xeon E5-2670 machine (32 threads).

When I begin to open multiple instances of matlab, matlab on the 4960x machine will, every few seconds, beomce slightly unresponsive (curser not moving), but overall it is not too bad. However, on the Xeon machine, after about 14 instances are open, it takes a systematically increasing amount of time to open additional instances. Even though NO cpu power is being consumed, Matlab is doing 'something' that is making it go very slow, and it becomes very annoying to deliver commands. It may take several minutes for each instance to open after about 20-24 are opened.

This problem does not exist in similar programs like MS excel.

So my question is, what in the world is Matlab doing? It is not taking up CPU power, but it becomes very slow to load, and later remains somewhat bogged down even after it is open. On the other hand, once all instances of matlab are open (up to 32 on my xeon machine), they will execute code nice and fast.

Answer 1

[per isakson]

On my five years old vanilla desktop with four cores (Intel Quad Q9600) I can open four Matlab instances without seeing "increasing amount of time to open additional instances."

[Christopher]

this seems consistent with the slowdown being related to how many instances are open, and not the speed or core count of your computer.

This is also consistent with the fact that matlab behaves slowly even with little or no cpu utilization.

[per isakson]

Based on my reading of your question, I though that on your systems it took longer to start the second instance than the first and longer to start the third than the second, etc.

That is not the case on my system.