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I recently noticed that Dropbox is taking about 50-90% of my CPU for more than just a few seconds sometimes - mostly when downloading/syncing many or large files.

Still, I guess that even when syncing a lot of data, there's no reason to use that much CPU (perhaps network or disk..)

Any ideas or suggestions? How can I make Dropbox use less CPU?

(running on Ubuntu 12.04 on Lenovo X220 with SSD Drive)

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I think that is a bug and you should contact dropbox for that, I will install it on Ubuntu 12.10 for you to check that(downloaded from the site or the software centre?) – Dr_Bunsen Oct 25 '12 at 18:22
The nautilus-dropboxextension downloads dropbox from their site. – Uri Herrera Oct 25 '12 at 18:26
@UriHerrera I'm not sure I understood what you mean? – yoav85 Oct 25 '12 at 22:12
One thing I do is start dropbox with a niceness of 18. Perhaps this would help your situation too. – Scott Wilson Apr 22 '13 at 18:28
This question is referred to in Super User question Dropbox causes high CPU usage on Mac OS X 10.8.2 (Mountain Lion). – Peter Mortensen Nov 24 '13 at 12:24
up vote 6 down vote accepted

Dropbox computes a hash of all files that it's going to sync, it uses it both to determine if they changed and to avoid uploading content that is already in their cloud (another customer has the same file).

Calculating hashes takes CPU power. It's usually noticeable at login.

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I see.. I guess that might be the reason - though it's still quite annoying sometimes! Thanks :) – yoav85 Oct 26 '12 at 16:54
maybe some system way, renice it to 19? – Aquarius Power May 2 '14 at 17:52
you can use cpulimit – Aquarius Power Aug 19 '14 at 22:59

Good shout with using cpulimit.

I found this could be simplified (when logged as root) to

cpulimit -e dropbox -l 10

where -l specifies percentage of CPU. Note this is for total CPU over all cores, so a dual core would have a limit of 200


cpulimit -e dropbox -l 10
Process 2641 detected
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Could be useful in the future, thanks! – yoav85 Aug 6 '14 at 7:48
that would require sudo password, tho adding that line to sudoers will do the trick I guess – Aquarius Power Aug 19 '14 at 22:53
@AquariusPower If you were not logged in as root then it would indeed require sudo. (I was logged in as root - edited to clarify) thanks – alleyoopster Aug 13 '15 at 9:52

Perhaps there is more to it than the problem of hashing.

One thing that I find strange is that with lsof | grep dropbox I do not see many open files under ~/Dropbox for the dropbox process.

What I did was to aptitude purge all packages related to dropbox, rm -r the 3 ~/.dropbo* folders (but not the ~/Dropbox folder), and then enable partner repositories and aptitude install nautilus-dropbox. Whether this procedure is problematic I do not know.

After a while (an hour?) with the new install and with dropbox CPU load I no longer see the load, so apparently the problem is solved. Perhaps the purging has helped or I just had a very large batch of files that needed updating.

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Thanks! I'll give it a try the next time something like this happens again. – yoav85 Mar 20 '13 at 22:34
I have already nautilus-dropbox and only one ~/.dropbox, my cpu usage and sysload is high :( – Aquarius Power May 2 '14 at 17:52

You can limit the cpu usage of any application this way:

#nPidDropbox=`ps -A -o pid,comm |egrep " dropbox$" |sed -r "s'^ *([[:digit:]]*) .*'\1'"`
nPidDropbox=`pgrep dropbox`

renice -n 19 `ps -L -p $nPidDropbox -o lwp |tr "\n" " "`
cpulimit -p "$nPidDropbox" -l 10

The first line of code is just a pid guesser. The 2nd line is to help cpulimiter work better while not requiring sudo.

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This happens to me frequently even when Dropbox is not actually syncing anything (there the hashing answer makes sense to me). My quick solution is to simply set Dropbox to stop syncing. Even tho it isn't actually syncing anything this seems to kill the CPU usage. Just have to remember to turn it back on later.

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