Remove first result from measurement

[tk26eng]

What this patch does to fix the issue.

This patch excludes first result from performance measurement because a first result includes some initialization time to read some data into memory.
That can be seen especially when we use pb file as model.

Below is the compared result of run.py which we use a same pb file

• Before
  INFO:main:Function _run took 0.3625333949457854 seconds to complete
  INFO:main:Function _run took 0.007619671057909727 seconds to complete
  INFO:main:Function _run took 0.007477258099243045 seconds to complete
  INFO:main:Function _run took 0.0068569539580494165 seconds to complete
  INFO:main:Function _run took 0.006867909105494618 seconds to complete
  INFO:main:Function _run took 0.007176596904173493 seconds to complete
  INFO:main:Function _run took 0.007123536895960569 seconds to complete
  INFO:main:Function _run took 0.007711157901212573 seconds to complete
  INFO:main:Function _run took 0.007052185945212841 seconds to complete
  INFO:main:Function _run took 0.007207290967926383 seconds to complete

• After
  INFO:main:Function _run took 0.00717798201367259 seconds to complete
  INFO:main:Function _run took 0.009376114001497626 seconds to complete
  INFO:main:Function _run took 0.01757289608940482 seconds to complete
  INFO:main:Function _run took 0.005577495088800788 seconds to complete
  INFO:main:Function _run took 0.0052312680054455996 seconds to complete
  INFO:main:Function _run took 0.004525961121544242 seconds to complete
  INFO:main:Function _run took 0.004832894075661898 seconds to complete
  INFO:main:Function _run took 0.004257153021171689 seconds to complete
  INFO:main:Function _run took 0.0041026161052286625 seconds to complete
  INFO:main:Function _run took 0.004274927079677582 seconds to complete

Link to any relevant issues or pull requests.

Fix #929

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[iizukak]

OA

[iizukak]

@kchygoe This PR solve your issue. What do think?

[kchygoe]

LGTM, thx

[tfujiwar]

Readability Approval

[tk26eng]

/ready

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[tfujiwar]

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