Minecraft low FPS?

So I hosted a lan session, Minecraft server, with only one friend and I have a pretty powerful computer, nVidia RTX 2080, Intel Core I7 8086k 4GHz and minecraft client usually runs at about 1000 FPS. However, when my friend joined it went to 40 FPS.

Any ideas? Should I try optifine? Does anyone else hosting Minecraft servers have the same issue? If so did you sort it out?

Btw we’re hosting 1.8 Minecraft servers cause they’re the best.