Tested on Minecraft 1.8.0 on Windows 10/Java 1.8.0_25. Graphics Card is NVIDIA GT745M. Optifine is installed, version 1.8.0 HD U D5.

I isolated this issue down to EiraIRC -- this issue does not exist if the mod is disabled.

I am able to provide any more configs as needed.

On build 258.

Can you try disabling the fancy overlay (/irc config global eirairc_enableFancyOverlay false) and see if that fixes it?

Can you try disabling the fancy overlay (/irc config global eirairc_enableFancyOverlay false) and see if that fixes it?

Appears to have done the trick after a full game restart. Will keep you posted if it comes back.