# OpenGL2 reslice performance issues on windows (moved)

**URL:** <https://discourse.slicer.org/t/opengl2-reslice-performance-issues-on-windows-moved/1914>\
**Category:** Uncategorized\
**Created:** [January 23, 2018, 4:44pm UTC](https://discourse.slicer.org/t/opengl2-reslice-performance-issues-on-windows-moved/1914 "2018-01-23T16:44:14Z")\
**Posts on this page:** 1\
**Showing post:** 3

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**Author:** ![pieper](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/pieper/32/8_2.png) [@pieper](https://discourse.slicer.org/u/pieper)\
**Post date:** [January 18, 2018, 3:58pm UTC](https://discourse.slicer.org/t/opengl2-reslice-performance-issues-on-windows-moved/1914/3 "2018-01-18T15:58:37Z")

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@lassoan

> [@Vtk python does not import on today's windows nightly](https://discourse.slicer.org/t/vtk-python-does-not-import-on-todays-windows-nightly/1868/9):
>
> Yes, this is a known issue - see details and workarounds here.

Yes, that’s what I meant by ‘the OpenGL2 issue’

> [@Vtk python does not import on today's windows nightly](https://discourse.slicer.org/t/vtk-python-does-not-import-on-todays-windows-nightly/1868/9):
>
> @pieper Can you try if disabling “Threaded optimization” (in Windows Control Panel -\> NVidia Control Panel) makes it better?

I tried a bit but it didn’t obviously help. I changed the setting to Off and restarted Slicer. Do you need to restart the machine or something to make it work? In any case we should try to get to the heart of the issue because users won’t want to change that level of config just to run Slicer.

> [@Vtk python does not import on today's windows nightly](https://discourse.slicer.org/t/vtk-python-does-not-import-on-todays-windows-nightly/1868/10):
>
> vtkmodules package is not expected to exist in the current nightly

must happen during the installer step then?

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