<div dir="ltr"><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><br>
Note that this is made at the expense of the 20% slowing down an iteration.<br>
<br>
$ ./python -m timeit -s "d = dict.fromkeys(range(10**6))" -- "list(d)"<br>
Python 3.5: 66.1 msec per loop<br>
Python 3.6: 82.5 msec per loop<br>
<br></blockquote><div><br></div><div>Are two Pythons built with same options?</div><div><br></div><div>In my environ:</div><div><br></div><div>~/local/python-master/bin/python3 -m timeit -s "d = dict.fromkeys(range(10**6))" 'list(d)'</div><div>Python master (8cd9c) 100 loops, best of 3: 11 msec per loop </div><div>Python 3.5.2 100 loops, best of 3: 11.6 msec per loop</div><div><br></div><div>And dict creation time is:</div><div><br></div><div>~/local/python-master/bin/python3 -m timeit "d = dict.fromkeys(range(10**6))"<br></div><div>Python master  10 loops, best of 3: 70.1 msec per loop</div><div>Python 3.5.2  10 loops, best of 3: 78.2 msec per loop</div><div><br></div><div>Both Python is built without neither `--with-optimizations` or `make profile-opt`.</div><div><br></div></div></div>