Here's the patch performance difference before and after the patch:

Before:

Sun May 20 21:42:32 2018    prof1.stat

         1188991 function calls (1188851 primitive calls) in 4.821 seconds

   Ordered by: cumulative time

   ncalls  tottime  percall  cumtime  percall filename:lineno(function)
     18/1    0.006    0.000    4.824    4.824 {built-in method builtins.exec}
        1    0.000    0.000    4.824    4.824 inspect_stack_perf.py:1(<module>)
        1    0.001    0.001    4.790    4.790 inspect_stack_perf.py:22(load_nodes)
      421    0.001    0.000    4.787    0.011 inspect_stack_perf.py:5(__init__)
      421    0.001    0.000    4.786    0.011 C:\Users\ppandey\AppData\Local\Continuum\Anaconda3\lib\inspect.py:1492(stack)
      421    0.011    0.000    4.785    0.011 C:\Users\ppandey\AppData\Local\Continuum\Anaconda3\lib\inspect.py:1464(getouterframes)
     4630    0.031    0.000    4.770    0.001 C:\Users\ppandey\AppData\Local\Continuum\Anaconda3\lib\inspect.py:1425(getframeinfo)
      420    0.001    0.000    4.739    0.011 inspect_stack_perf.py:9(add_child)
    13994    4.159    0.000    4.159    0.000 {built-in method nt.stat}
     4630    0.042    0.000    3.223    0.001 C:\Users\ppandey\AppData\Local\Continuum\Anaconda3\lib\inspect.py:760(findsource)
     9322    0.043    0.000    2.960    0.000 C:\Users\ppandey\AppData\Local\Continuum\Anaconda3\lib\inspect.py:680(getsourcefile)
     9322    0.011    0.000    2.832    0.000 C:\Users\ppandey\AppData\Local\Continuum\Anaconda3\lib\genericpath.py:16(exists)
     4630    0.016    0.000    1.339    0.000 C:\Users\ppandey\AppData\Local\Continuum\Anaconda3\lib\linecache.py:53(checkcache)
     4630    0.097    0.000    0.364    0.000 C:\Users\ppandey\AppData\Local\Continuum\Anaconda3\lib\inspect.py:714(getmodule)
     4692    0.008    0.000    0.135    0.000 C:\Users\ppandey\AppData\Local\Continuum\Anaconda3\lib\inspect.py:702(getabsfile)
     4754    0.008    0.000    0.091    0.000 C:\Users\ppandey\AppData\Local\Continuum\Anaconda3\lib\ntpath.py:538(abspath)
     4754    0.036    0.000    0.074    0.000 C:\Users\ppandey\AppData\Local\Continuum\Anaconda3\lib\ntpath.py:471(normpath)
   162600    0.071    0.000    0.071    0.000 {built-in method builtins.hasattr}



After the patch:

Sun May 20 21:39:44 2018    prof2.stat

         2639991 function calls (2639727 primitive calls) in 2.841 seconds

   Ordered by: cumulative time

   ncalls  tottime  percall  cumtime  percall filename:lineno(function)
     18/1    0.005    0.000    2.844    2.844 {built-in method builtins.exec}
        1    0.000    0.000    2.844    2.844 inspect_stack_perf.py:1(<module>)
        1    0.001    0.001    2.814    2.814 inspect_stack_perf.py:22(load_nodes)
      421    0.001    0.000    2.812    0.007 inspect_stack_perf.py:5(__init__)
      421    0.001    0.000    2.811    0.007 C:\Users\ppandey\AppData\Local\Continuum\Anaconda3\lib\inspect.py:1492(stack)
      421    0.010    0.000    2.810    0.007 C:\Users\ppandey\AppData\Local\Continuum\Anaconda3\lib\inspect.py:1464(getouterframes)
      420    0.001    0.000    2.802    0.007 inspect_stack_perf.py:9(add_child)
     4630    0.029    0.000    2.795    0.001 C:\Users\ppandey\AppData\Local\Continuum\Anaconda3\lib\inspect.py:1425(getframeinfo)
     4630    0.040    0.000    2.380    0.001 C:\Users\ppandey\AppData\Local\Continuum\Anaconda3\lib\inspect.py:760(findsource)
     4674    1.631    0.000    1.631    0.000 {built-in method nt.stat}
     4630    0.014    0.000    1.630    0.000 C:\Users\ppandey\AppData\Local\Continuum\Anaconda3\lib\linecache.py:53(checkcache)
13952/13890    0.281    0.000    0.907    0.000 C:\Users\ppandey\AppData\Local\Continuum\Anaconda3\lib\inspect.py:714(getmodule)
9322/9260    0.038    0.000    0.703    0.000 C:\Users\ppandey\AppData\Local\Continuum\Anaconda3\lib\inspect.py:680(getsourcefile)
    13952    0.018    0.000    0.259    0.000 C:\Users\ppandey\AppData\Local\Continuum\Anaconda3\lib\inspect.py:702(getabsfile)
    14014    0.017    0.000    0.215    0.000 C:\Users\ppandey\AppData\Local\Continuum\Anaconda3\lib\ntpath.py:538(abspath)
   478166    0.177    0.000    0.177    0.000 {built-in method builtins.hasattr}


Total runtime reduced from 4.8 s to 2.8 s, and the major difference can be seen in the `nt.stat` call. This is on a machine with SSD. In workplace where python is installed in cluster on nfs, I'm sure the performance is worse.