# speed up registration process

**URL:** <https://discourse.itk.org/t/speed-up-registration-process/3667>\
**Category:** Algorithms\
**Tags:** registration\
**Created:** [November 30, 2020, 3:00pm UTC](https://discourse.itk.org/t/speed-up-registration-process/3667 "2020-11-30T15:00:32Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![pierrectl](https://discourse.itk.org/user_avatar/discourse.itk.org/pierrectl/32/1420_2.png) [@pierrectl](https://discourse.itk.org/u/pierrectl)\
**Post date:** [November 30, 2020, 3:00pm UTC](https://discourse.itk.org/t/speed-up-registration-process/3667/1 "2020-11-30T15:00:32Z")

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hello everyone,  
I currently develop a registration algorithm using itk framework. Everything seems to work well, except that execution time is very long, especially metric computation (as expected). I have one question: is the registration process multi threaded? More specifically, I do not understand what WorkUnits are? Are they similar to threads?

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**Author:** ![dzenanz](https://discourse.itk.org/user_avatar/discourse.itk.org/dzenanz/32/1093_2.png) [@dzenanz](https://discourse.itk.org/u/dzenanz)\
**Post date:** [November 30, 2020, 5:38pm UTC](https://discourse.itk.org/t/speed-up-registration-process/3667/2 "2020-11-30T17:38:09Z")

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Registration is parallelized. In Wikipedia article on [thread pool](https://en.wikipedia.org/wiki/Thread_pool), `WorkUnits` are called tasks.

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**Author:** ![pierrectl](https://discourse.itk.org/user_avatar/discourse.itk.org/pierrectl/32/1420_2.png) [@pierrectl](https://discourse.itk.org/u/pierrectl)\
**Post date:** [December 1, 2020, 9:25am UTC](https://discourse.itk.org/t/speed-up-registration-process/3667/3 "2020-12-01T09:25:27Z")

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okay, thank you for the info @dzenanz