Between 2005 and 2012 the finder icon in my dock (OS 10.4.11 ppc) looked sharp but of late it's been looking vague. Then recently my Safari (not the latest security update) was behaving weirdly, and during that time lo and behold the icon was looking sharp again?!? Would love to add small sized screenhots to explain. For lack, it's this icon: http://s.macgasm.net/wp-content/uploads/2011/01/Flurry-of-Mac-Apps-Updated-this-Week-17-09-2010-2.jpg
Hoarding photos on your phone?
Those picture are hogging memory and could be slowing down your phone.