This sounds fairly normal for a 1/4" bit. You could quiet some operations using a 1/2" bit where appropriate.
That said, here are a some things to double-check to optimize you tool that might help quiet it.
Make sure that the collet is snapped into the collet nut before placing it in the spindle. Also be sure to knock out any dust buildup whenever you've changing bits.
You might experiment with different chip loads. Work within the guidelines provided by the help page to see if perhaps a higher chipload might quiet it down. Currently you're toward the lower end for most materials.
Finally have a look at the ramping values on your machine. This link describes the ramping feature well.
http://www.shopbotblog.com/index.php...m-performance/