Time Dilation: Current vs Massless Universe

[CzarBrent]

Disclaimer: I have no formal education in physics.

I watched a TedTalk http://www.tedxamsterdam.com/video-wubbo-ockels-on-time-and-gravity/ and it got me thinking. Dangerous, I know. As I understand both velocity and gravity have an effect on our perception of time. How much does our current universe affect our measurement of time, and is there a zero point?

The Earth is rotating at ~1K mph around its axis
We're zipping around the sun at ~67k mph
Our position in the galaxy is rotating at ~ 671K mph
And then were being pulled by "The great attractor" at 14M mph.
If this wasn't enough we have the mass of earth, sun, galaxy, dark matter, etc... further causing distortion.

What would be the time dilation between a clock in a static near massless universe (save the clock and observer) and our current reference?

 

[mfb]

There is no massless universe to compare clocks with, but our clocks are a bit slower than clocks in big voids. The difference is roughly 1-2 parts in a million, or 24000 years since the Big Bang. Completely negligible.

Note that you have to be stationary with respect to the cosmic microwave background to have a meaningful definition of "age of the universe".