[Admins]

These are two different things:
When the Facebook version is becoming slower/laggy (downloading gfx or so) then the input is lagging, not easy to resolve but we are working on speeding up the client.

Keys getting stuck on v5/v6: the way keyboards are built is the reason you cannot press more than 3 keys at once, sometimes can be less depending on what kind of key you press. If you do more than a key can get stuck, then you need to press and release it again to fix it. Since this is a hardware limitation it's not easy to fix, other than not using similar keys (the arrow keys are often not using the same cable for transmitting their state as the A/S/D/J/K/L keys).