> For the complete documentation index, see [llms.txt](https://docs.d5render.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.d5render.com/user-guide/resource/why-does-the-operation-lag-when-previewing.md).

# Why does the operation lag when previewing?

When previewing, you can check the fps value in Menu-View-Show Statistics to check how many frames per second are transmitted when running the current scene; the fps value during previewing does not affect the actual rendering output result. 

If the fps value is lower than 20 when running the scene, there will be a lagging feeling; the fps value will be reduced when the graphics memory is high. You can check the current graphics memory usage by viewing Task Manager - Performance - GPU - View - Dedicated GPU Memory. 

If memory usage is high, consider using Smooth Mode during preview or combining it with ↓ content to optimize memory usage.

<figure><img src="/files/KTrh0cCpMrXJYk7lFIQJ" alt=""><figcaption></figcaption></figure>

> How to view and optimise video memory usage?