Hi! I use optifine to increase my FPS for the modpack server I play on with my friends.
Considering Minecraft is already littered with unskippable warnings about how the client is modded, we acknowledge why Twilight Forest has decided to give this warning on game start, however we would like to request that this message appears just once and not every time the game is done loading, as it's extremely infuriating to have "pop-ups" everywhere. Thanks.

You can disable it in the client config

where exactly?
It's happening with me

You can disable it in the client config