There's just one big issue :
I'm not sure, but it would allow some precomputations to be done at compile-time and kill a good half of every problem. (Moreover some submissions could compile for years...)
On the other hand, it could be good to see the incoming of C++11, with integration of compile time in the total time, so a compile-time too big led to TLE.
Just a 2c argument of a non C++ user.