* Turned the msg() and debug() functions into macros, since they

turned out to be a huge performance bottleneck (the text to printed
  would always be evaluated, even when it was above the verbosity
  level).  This reduces fix-ng execution time by over 50%.

  gprof(1) is very useful. :-)

src/libnix/exec.cc

@@ -110,7 +110,7 @@ void runProgram(const string & program,
     
     if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) {
 	if (keepFailed) {
-	    msg(lvlTalkative, 
+	    printMsg(lvlTalkative, 
 		format("program `%1%' failed; keeping build directory `%2%'")
                 % program % tmpDir);
 	    delTmpDir.cancel();