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Asked by ondrej
on 11 May 2012

The CPU load is very high all the time. Even fresh after starting matlab with no variables and no programs running.

Its about 35%-45% all the time. Here you can see the trace in time of Matlabs cpu load:

Setup: r2012a on win7 64bit, 8gb ram, 200gb free disk space,intel U9400 2core cpu(laptop),java Version 6 Update 31.

What can be causing this?

thx

## 7 Comments

## per isakson

Direct link to this comment:http://www.mathworks.com/matlabcentral/answers/38094#comment_79002

Did you ask Technical Support? Matlab shouldn't do that. Something is wrong.

## Germán

Direct link to this comment:http://www.mathworks.com/matlabcentral/answers/38094#comment_132152

I'm getting the exact same behavior, I'm running R2012a on linux. To make it worse I always leave 2 sessions open which use 100% of of 2 cores when idle.

## Walter Roberson

Direct link to this comment:http://www.mathworks.com/matlabcentral/answers/38094#comment_132194

Datapoint: I never get this behavior on OS-X Lion with R2012a.

## Germán

Direct link to this comment:http://www.mathworks.com/matlabcentral/answers/38094#comment_141709

For the sake of people who might be having the same issue I finally solved it. It was the JxBrowser renderer, the issue starts after the first time I open a help window. In order to use the HTML renderer I included

on my startup.m and that stopped the high cpu usage.

## Walter Roberson

Direct link to this comment:http://www.mathworks.com/matlabcentral/answers/38094#comment_141732

Thanks for the update.

## Christoph

Direct link to this comment:http://www.mathworks.com/matlabcentral/answers/38094#comment_194567

There is now an answer from the Mathworks Support team to this very question: http://www.mathworks.com/matlabcentral/answers/114915-why-does-matlab-cause-my-cpu-to-spike-even-when-matlab-is-idle-in-matlab-8-0-r2012b

## ondrej

Direct link to this comment:http://www.mathworks.com/matlabcentral/answers/38094#comment_222724

HTMLRENDERER does NOT solve it. sad. very sad. octave and R...