Sometimes during the game there is a bug, due to which your buttons respond slowly when you type in the chat, and it's too hard even to press a backspace.
That didn't come before 3xx, and also as I see, it happens if there are many objects or explosions at the map, but damnit, that didn't happen before! And sometimes it doesn't only affect the chat, gameplay too.
The same (and worse) behaviour was also being detectable in 300 with the "fast chat opening" bug (which was also touching the Esc menu), due to which the buttons lagged as hell everywhere and everytime.
PS: I use vsync without framelimit, Triple buffering is off, Windowed and GameLogging are on, Anti aliasing is off.