ok I ran it again, but note the machine was under use the full time so the results are likely have no meaning.

python perf.py -r -b default /tmp/normal/bin/python3 /tmp/opt/bin/python3

Min: 0.399279 -> 0.376527: 1.06x faster
Avg: 0.410819 -> 0.383315: 1.07x faster
Significant (t=49.29)
Stddev: 0.00450 -> 0.00330: 1.3631x smaller

### etree_iterparse ###
Min: 0.639638 -> 0.630989: 1.01x faster
Avg: 0.658744 -> 0.641842: 1.03x faster
Significant (t=14.82)
Stddev: 0.00959 -> 0.00617: 1.5557x smaller

### etree_parse ###
Min: 0.433050 -> 0.377830: 1.15x faster
Avg: 0.444014 -> 0.389695: 1.14x faster
Significant (t=43.28)
Stddev: 0.01010 -> 0.00745: 1.3570x smaller

### tornado_http ###
Min: 0.335834 -> 0.326492: 1.03x faster
Avg: 0.346100 -> 0.334186: 1.04x faster
Significant (t=13.66)
Stddev: 0.01024 -> 0.00689: 1.4864x smaller

The following not significant results are hidden, use -v to show them:
2to3, django_v2, etree_process, fastpickle, fastunpickle, json_dump_v2, json_load, nbody, regex_v8.

/tmp$ /tmp/normal/bin/python3 -c 'import timeit; print(timeit.repeat("dict(a=5, b=2)"))'
[0.5112445619997743, 0.5141109460000735, 0.5185121280010208]
/tmp$ /tmp/opt/bin/python3 -c 'import timeit; print(timeit.repeat("dict(a=5, b=2)"))'
[0.4426167189994885, 0.4465744609988178, 0.4467797579982289]