MATLAB: Is Matlab slow with large objects in the workspace even when RAM is not limited

Question

I'm running Matlab on a machine with 200 GB of ram, yet Matlab slows down horribly when I store large (~10GB) objects in the workspace.

To test, I've tried running tic; 1+1; toc.

This snippet sometimes runs nearly instantaneously (as one would expect) but often takes minutes! I cannot discern a pattern in the runtime–it seems random. However, even when it runs slowly (5 min for example), toc still shows that it ran in milliseconds. While the command is running, I'm able to use the computer and Matlab normally (except the command window of course.)

Scripts also run extremely slowly.

How can I speed things up?

Answer 1

Close the workspace browser or hide its tab. It may be that changing the workspace preference for calculating statistical values to a smaller number will help.

After running any code, but before returning to the command line, anytime a base workspace variable could have changed (usually scripts or commands) the workspace browser needs to refresh its list of variables, values and statistics including variable size. For large object structures or cell arrays this can take a long time to determine.