Old builds compiled under 1.7.2 still work at the "original framerates." If I could make a seperate 1.7.2 install I would expect it to be the same. Performance changed immediately after the update.
Framerate values we are talking about are about 1200fps in windowed mode down to about 600fps. Now that is not a big deal initially, of course, but I run our development on a fairly beefy system and the graphics are pretty bare bones right now. I found that a little alarming considering what we have planned, and we still need to aim for a "baseline" target.
Running fullscreen syncs up at 60hz for me as normal.
I have not yet tested the build on a different machine but can do so in the next few days. Let me know if there is anything else I can do to help. I am pretty curious.