All the developers in my team here have the same problem - when NetBeans is unpacking the index for Sonatype Repository the system becomes very, very slow. I hope that there is some parameter somewhere so we can reduce the priority of that process in order to make it "behave"?
UPDATE: Thanks to @sashoalm for reminding me about the disk I/O. I have noticed that the process does lots of disk I/O and that probably makes the system unresponsive.
It has a nasty habit of starting at the worst possible time, so we had to turn it off…
OK, I have found a solution. I am not particularly happy with it, but anything is better than nothing.
Luckily, I use Linux exclusively, so I simply reniced the java process that is taking all the system resources. A simple renice -p <java PID here> -n 10 did the job, and the whole system is now responsive as before.