Matlab help, doc commands very slow

Question

I can't put my finger on why it's doing this, but since a few days help takes a lot of time to show. Either inline (selecting a function, selecting "help for"), or by using the commands doc or help. The command doc cmdname takes about 10 seconds to show the help window. I did, taking fwrite as example, try profile on;doc fwrite;profile viewer and digging through the rabbit hole I arrived on a private java matlab method which is taking forever:

tic;
com.mathworks.mlwidgets.help.HelpUtils.getDocCommandArg('matlab\fwrite', true);
toc 

Elapsed time is 9.993832 seconds.

Any idea what could be causing that issue? It also happens in safe mode, with no other running programs than MATLAB. I'd try a complete reinstall of MATLAB, but if I could avoid that that'd be great.

Answer 1

There are a couple of things that might be contributing to this issue, but given the information you've provided it's hard to say exactly what is going on.

When the R2012b help system initializes, it does a few tasks that can sometimes introduce a noticeable delay, mostly related to determining which MathWorks products are available and how you have your help preferences set up. 10 seconds would be unusual, but there is a possibility that this is what's causing the delay. If you're seeing the performance hit on your first use of the help system, but not again in the same MATLAB session, this is the likely cause. This behavior is improved in R2013a.

Other than initialization tasks, the Java call in question is a relatively straightforward search against the same search index that is used for searching the documentation. If you are finding that searching the documentation in the help browser is slow, this would be a hint that the performance issue lies somewhere within the help system's search functionality.

In either case, your best bet is probably to contact MathWorks technical support. It is likely that we can take a closer look at this and possibly come up with some sort of fix.