From the Cairo Dock FAQ:
I find the dock too flashy, can it be more sober?
Tip: try different themes, some are already very sober, like Dust-Sand or Elementary.
When you can do more you can do less ! You can for instance deactivate the "Icon effects" plug-in,
or deactivate the effect on mouse hovering in "Animated Icon" plug-in.
You can also decrease the zoom effect or lower the icons' reflect in the "Icon" module,
change the background colors in the "Background" module, or change the view to the "default" view in the "Views" module.
In brief, you can easily have something as sober as a gnome-panel, but this would be a shame ! ^_^
Right click on the dock, Cairo-Dock -> Configure go to the Icons module and change the Maximum zoom of the icons setting to 1 and the icons will no longer "grow" when you hover over them.