> 
> With 4.2.1, I take a C program and force it to be compile by the C++ compiler.
>   The compilation takes about twice as long (this is also true with 3.3.5).
> 
> Is this normal behavior?

It's expected that C++ takes longer to compile than C. With 4.2.1 you can see where the time is being spent in the 
compiler by using the -Wc,-ftime-report option. I would expect the difference in times would be doing the parsing and 
name lookups.

Regards,

Ryan Mansfield