On startup, Dropbox runs files indexing, which brings the system pretty much to a stand still for three minutes.
Is there a way to restrict Dropbox from accessing the hard disk, or decrease the priority of Dropbox's access to the hard disk?
Complementing the answer of Carlos D. Barranco, you can edit the launcher file located in /usr/share/applications/dropbox.desktop and permanently set a low priority start for dropbox.
In my case, it was also useful to limit the processor usage of dropbox. You can install package cpulimit: # apt-get install cpulimit
For example, to limit dropbox up to 20% processor usage: # cpulimit -b -e dropbox -l 20
In order to configure both low IO and low processing for dropbox automatically with the system launch, edit /usr/share/applications/dropbox.desktop and replace dropbox start -i by ionice -c 3 dropbox start -i && cpulimit -b -e dropbox -l 20
Command ionice will set idle priority for IO access and the parameter -l of cpulimit configures the processing limit in percentual values. More information on cpulimit can be found in: http://www.nixtutor.com/linux/changing-priority-on-linux-processes/
