[Jaunty] Screen brightness adjustment sluggish

In Ubuntu 9.04 (Jaunty), compared to Ubuntu 8.10 (Intrepid), screen brightness adjustment feels quite sluggish. The increments are very small, the time between each adjustment is a bit too long, and there's no acceleration (e.g., consistently holding down the screen dim/brighten button doesn't adjust more rapidly the longer it's held).

NOTE: This may not be Mactel specific (e.g., it could be the new GNOME behavior), but I'm reporting it here since I can not verify for other hardware, and am using the Mactel drivers for screen brightness adjustment.