timeit microbenchmarks on dict_version-8.patch, minimum of 10 runs.

$ ./python.orig -m timeit 'd={1: 0}; d[2]=0; d[3]=0; d[4]=0; del d[1]; del d[2]; d.clear()'
1000000 loops, best of 3: 0.292 usec per loop
$ ./python.version -m timeit 'd={1: 0}; d[2]=0; d[3]=0; d[4]=0; del d[1]; del d[2]; d.clear()'
1000000 loops, best of 3: 0.293 usec per loop

=> 1 nanosecond (0.3%) slower

$ ./python.orig -m timeit 'd={i:i for i in range(2**16)}' 'for i in range(2**16): d[i]=i-1' 'for i in range(2**16): d[i]=i+1' 'for i in range(2**15): del d[i]' 'd.clear()'
10 loops, best of 3: 21.2 msec per loop
$ ./python.version -m timeit 'd={i:i for i in range(2**16)}' 'for i in range(2**16): d[i]=i-1' 'for i in range(2**16): d[i]=i+1' 'for i in range(2**15): del d[i]' 'd.clear()'
10 loops, best of 3: 21.3 msec per loop

=> 0.1 ms (0.5%) slower