When you write a line of C you have a good idea of how much actual work it's going to make the computer do.
e.g. with for (i=0;i<10;i++) a[i]=i*i; you have a multiply, a store, and a comparison.
The same thing in a more abstracted language might involve looking stuff up in a symbol dictionary, mallocs, creating objects on the heap, reference counting, garbage collection, blahblahblah, hundreds and hundreds of cycles.
That's why I like C, you know what's going on underneath.