Comment 15 for bug 168648

GIMP uses fixed-size bitmap icons, Inkscape uses scalable SVG icons.

Under the "Misc" preferences there are now options to make the topmost and left toolbars use smaller sizes (as long as the theme is set with sizes you'd like). On OS X this gives me currently a minimum size of 573x546.

For extreme situations (such as the Asus Eee PC) the gtk rc file can be edited to have specific, smaller, icon sizes for Inkscape.