Still more software bloat (even further off topic)

Still more software bloat (even further off topic)

Maybe your friend simply didn't have enough RAM and GCC had to resort to using swap -- that would sure slow the process down to a crawl.

Oops! I forgot to mention that my friend attempting to compile Firefox from source code was doing so in Windows using Visual Studio .NET. He mentioned that he was able to hobble together some functionality but the running program had "various stability and reliability issues...".

I thought I read somewhere that the Win32 version of FF is compiled on Windows using Cygwin and/or MinGW using CMake, but I might be mistaken.

Yeah, well, that explains it. Cygwin is very slow at fork()ing, and 
several fork()s are involved in the process of compiling a single .o. 
There are tens of thousands of object files in Firefox.

(The sources for Firefox on my system clock in at a 'mere' 340Mb.)