Although it is logical to expect Quicksilver's metabolism to work faster, he's never been shown aged (like most other comic book characters).
He would be affected by time dilation, though.
The closer the object approaches the speed of light, the slower time flows within that object (or the less the flow of time affects the object, or maybe the slower physical processes flow within the object itself).
t' = t*sqrt(1-V^2/c^2) Where t' is dilated time. Subtract the ratio of square of speed to square of lightspeed from one and take square root of that.
If, for example, Quicksilver moves at 1% the speed of light, he is at nearly 3 000 km/s, and the ratio of squares of speeds will be 0.0001 (1% squared, or 0.01^2). Therefore, for him, time will move at 0.9999 of its stationary speed (well, let's not get too anal with significant digits).
To put it in perspective, if an observer is sitting in a chair watching Quicksilver run around at 1% speed of light, for every 100 years (36524 days) that the observer ages, Quicksilver will age 36520 days.
That is, of course, a negligible ratio, but suppose that Apocalypse amplified his speed to 10% of lightspeed...
Let's just ignore the fact that he's long surpassed the escape velocity (which he probably surpassed already while rescuing the inhabitants of Xavier School).