Desktop unresponsive while using dd

While 'burning' an .iso image to a usb drive, the desktop is intermittently unresponsive.

While the dd process is ongoing, I'm trying to perform other tasks, but sometimes the desktop is completely unresponsive to my commands (e.g. switching application, bringing up another window...); the system appears to be completely frozen and I have to wait about 1 minute before the system comes back up again. When the dd process has completed (10~15 minutes to burn a 2.2Gb .iso file), everything comes back to normal, so it's not something critical.

However, it would be nice to be able to use the system normally while dd is doing its deed. I understand that this must be a I/O saturation problem, with dd taking all the available bus bandwidth. Is there a way to limit/throttle the dd process so that it leaves some bandwidth available for normal user operation, even if it means that dd will take longer to complete its task?