The idea behind the timing clause is so that the program will know precisely when it started running, rather than when the pattern-matching was completed. Now, I did this test:

> (define func (eval code0))
> (time (func code0))
cpu time: 0 real time: 1 gc time: 0
'C

which reveals that the difference isn't significant. However, now that the code is out in the open, I'm not changing it.