I saw flashrom process use too many cpu time when I use it to write flashchip.
Then I strace the process, and found too many "clock_gettime(CLOCK_MONOTONIC...)" system call.
And located it to udelay.c line 39, in function clock_usec_delay().
So I replace the code with just  usleep(), as below,
 static void clock_usec_delay(int usecs)
 {
     usleep(usecs);
 }

And it still worked well, and use much less cpu time, and the time spend on erase&write a chip is basicly the same as before.

Also I write image to a flashchip and read it out with the modified flashrom many times, and the read out results are always same as the original image.

So why not use usleep() to save cpu time ?

BTW: I have used flashrom many years, it helped me a lot, thanks for your work, very grateful.