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Topic: IDE causes high cpu / fan usage (Read 12573 times) previous topic - next topic


"Westfw, thanks for giving me a nudge in the right direction!

I had a look, and the Arduino IDE contains  \java\bin\javaw.exe

Compiling a list of java versions supplied with IDE versions reveals that IDE 1.8.6 and 1.8.7 share the same version of java.
Arduino IDE version: 1.8.1
javaw.exe version: 8.0.1110.14

Arduino IDE version: 1.8.5
javaw.exe version: 8.0.1440.1

Arduino IDE version: 1.8.6
javaw.exe version: 8.0.1710.11

Arduino IDE version: 1.8.7
javaw.exe version: 8.0.1710.11

Arduino IDE version: beta 1.9
javaw.exe version: 8.0.1910.12

Arduino IDE version: Current hourly build
javaw.exe version: 8.0.1910.12

I then copied the java folder from IDE BETA 1.9 into the IDE 1.8.7 install folder and the fault is gone!

As a double check, I copied the java from 1.8.7 into beta 1.9 and the fault shows up in beta 1.9.

My conclusion is that the java supplied with Arduino IDE 1.8.6 and 1.8.7 (java version 8.0.1910.12) is the cause of the 30% CPU utilisation issue that some of us have seen.

You can run Arduino IDE 1.8.7 successfully simply by replacing the java folder, using the Arduino Beta 1.9 install as the source.

Does anyone (that has seen this fault before) care to test and confirm or deny this theory?



I renamed java folder (in "program files\arduino\") to java-old to save it. As we age, we learn how not to break things.
Copied a new java folder from 1.9.0 beta zip file.

I didn't notice fan (A/Cond makes more noise than my fan) but CPU use dropped from >50% as it should.
Now 2% when IDE window looses focus.

2% is much better when IDE window looses focus!! :)

>10 year old Toshiba L500 with Windows 7 (32 bit)
Laptop was getting sluggish switching to my schematic editor was why I chased this 'feature'

Thanks Mathew.


Replacing java folder of 1.9 beta version worked for me too. Thanks a lot.


Looking forward to seeing if this problem can be fixed on my system.
Right now looking at task manager (Win 10) with CPU (Intel i5) running at about 68% usage. Of that, 33% is down to one instance of IDE Java SE binary 32-bit and about the same for another instance. One instance has a COM port open with Serial Monitor running and the other just has sketches open.
Not being as experienced as most of the other contributors, I had trouble just finding the version of Java included with the IDE program. FWW, I opened the "release" file in Notepad ++ (ever dependable) where it comes up as version 1.8.0 171.
Currently running IDE 1.8.7 which needs an update to 1.8.8 or I might try changing the Java folder as suggested.
Thanks for all the efforts


Pleased to report that the update from 1.8.7 to 1.8.8 has so far completely eliminated this problem.
The IDE and Java were consuming more CPU resources than all the applications put together and I am certain that it caused several eventual crashes or freezes of the PC as a whole.
For reasons nothing to do with Arduino, I had to leave two instances of the IDE running for well over a week with one churning out serial monitor data as well. The Java CPU usage on both instances was in the region of 1% (unchanged) and overall CPU usage running at 8%. Previously, this would have been knocking on 70-80% usage, most of it down to Java.
Glad to see the back of it and a return to "normal" running.
Thanks to whoever fixed it


Thanks for the detective work, just spotted a maxing core tonight. Kicks in after about 2 mins of running the arduino IDE with it sitting idle. Again its the javaw process. Will try the update later and see if it fixes things


Spoke too soon.
After days of good running, CPU back up to 30% on one IDE instance.


+1 on high pcu/fan usage when either serial monitor or plotter are open. My cpu almost smoking and its a brand new 8700. Close it, and everything gets real quiet immediately.

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