# FPS drop using Syphon

**URL:** <https://discourse.libcinder.org/t/fps-drop-using-syphon/1590>\
**Category:** CinderBlocks\
**Created:** [November 16, 2019, 9:53pm UTC](https://discourse.libcinder.org/t/fps-drop-using-syphon/1590 "2019-11-16T21:53:36Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![couleurs](https://yyz2.discourse-cdn.com/flex030/user_avatar/discourse.libcinder.org/couleurs/32/99_2.png) [@couleurs](https://discourse.libcinder.org/u/couleurs)\
**Post date:** [November 16, 2019, 9:53pm UTC](https://discourse.libcinder.org/t/fps-drop-using-syphon/1590/1 "2019-11-16T21:53:36Z")

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Hi folks, I’m starting to use Syphon and its Recorder app to capture a video of the output of my Cinder app. Thanks to [https://github.com/gaborpapp/Cinder-Syphon](https://github.com/gaborpapp/Cinder-Syphon) I’ve been able to get setup pretty easily with a Syphon server to publish the output of my app to the Recorder. Everything works as expected except I noticed a big FPS drop from 60 to 30 when I call `publishScreen()`. Even when I draw just one red rectangle the FPS is 30.

My understanding was that Syphon was supposed to be very fast because the frame content doesn’t leave the GPU, so I’m wondering if I’m doing something wrong? Is Syphon being capped at 30 somehow? Not sure that’s relevant but my app is drawing two windows and I’m only publishing the output of one of them.

Thanks for your help 🙂

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**Author:** ![gabor\_papp](https://yyz2.discourse-cdn.com/flex030/user_avatar/discourse.libcinder.org/gabor_papp/32/769_2.png) [@gabor\_papp](https://discourse.libcinder.org/u/gabor_papp)\
**Post date:** [November 16, 2019, 10:43pm UTC](https://discourse.libcinder.org/t/fps-drop-using-syphon/1590/2 "2019-11-16T22:43:21Z")

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Use `publishTexture` instead of `publishScreen`. `publishScreen` downloads the window contents from the GPU, which is slow. Draw into an `Fbo` and publish the `Fbo` texture instead.

Two windows can also cause 30 fps if you wait for vertical sync, but I think this is not the issue here.

-Gabor

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**Author:** ![couleurs](https://yyz2.discourse-cdn.com/flex030/user_avatar/discourse.libcinder.org/couleurs/32/99_2.png) [@couleurs](https://discourse.libcinder.org/u/couleurs)\
**Post date:** [November 16, 2019, 10:54pm UTC](https://discourse.libcinder.org/t/fps-drop-using-syphon/1590/3 "2019-11-16T22:54:37Z")

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@gabor_papp that fixed it! Thanks so much for coming to the rescue once again 😍