It's why going to the next larger size monitor has more of an effect than you think. The size is given in terms of the diagonal, but moving that up 10% increases the area by 21%; 1.1 squared is 1.21.
I have an unfortunate tendency to run the display resolution up. (Still using a CRT. What can I say?) "Oooh.... 1800 x 1440...." After all, it means I can crank up the size of fonts to compensate and the result will look better.
Unfortunately, the graphics card's work load goes up proportionally to the area as well, poor thing. One of the reasons the Sabayon Linux Live DVD was flying at 50+ fps is that it didn't have the screen resolution cranked.
So, I've restrained myself and dropped back, and my SL experience should be better as a result. More evidence that I'm not a gamer; all the gamers out there who read this will probably respond "Well, duh..."
P.S. The other disadvantage is that graphics on web sites are sized based on a guess as to the viewer's probable resolution, so reading, say, Day by Day becomes an exercise in futility for aging eyes at high resolution. I think my eyes will thank me for this decision.