Why having two graphics cards can slow down Lychee Slicer, and how to fix it
Some gaming PCs have two graphics cards, useful for gaming, but it can work against you when it comes to 3D printing, since Lychee Slicer may end up using the weaker (usually integrated) card instead of your dedicated GPU.
To fix this, go to File → Preferences → Global Settings → Performance. Check that Active GPU shows your dedicated card, make sure Eco mode is off, and set the performance profile to High, then restart Lychee Slicer. See Graphics and Performance Settings for details. On older versions of Lychee Slicer, turn on Force High GPU Mode in the same place instead.
If you're still experiencing slow performance after this, you can also override which GPU Windows assigns to Lychee Slicer directly in your Windows display settings, and it's worth checking that your graphics drivers are up to date.