When I first read through the code, my first thought was that load on the system would impact the calculations. So I did a quick and dirty test, taking advantage of a big, ugly query I had. I added a timer to the whole getdate loop and ran with no other queries running. Then I started up 5 independent queries and ran the getdate loop. The load definitely impacted the calculation. (Note: this was run on SQL 2005 server.)

-- test impact of load on getdate() calculation.

-- (normal load on system)

16718

3.34807

loop getdate 55973 Milliseconds duration

-- start up 5 big, ugly queries

49369

5.01339

loop getdate 247506 Milliseconds duration