Why optimization mode is slower than normal mode?

[Leo Jay]

Hi all,

I'm using python 2.6 in a windows xp box, when I try pystone, I get:
C:\Python26\Lib\test>python pystone.py 500000
Pystone(1.1) time for 500000 passes = 5.93632
This machine benchmarks at 84227.3 pystones/second

C:\Python26\Lib\test>python -OO pystone.py 500000
Pystone(1.1) time for 500000 passes = 6.00515
This machine benchmarks at 83261.8 pystones/second

I tried many times, and get the same result.

Why optimization mode is slower than normal mode?

 

[Cro]

Not-optimised:
Pystone(1.1) time for 1000000 passes = 12.8366
This machine benchmarks at 77902 pystones/second

Optimised:
Pystone(1.1) time for 1000000 passes = 13.0574
This machine benchmarks at 76584.8 pystones/second

It is probably the way it should be.