Efficiency is not measured by how toxic you are or how stressed you can be in a given task. The game plan is simply not to look like you're not doing anything and you're oh so relaxed with what you're doing. What can you do if you're simply efficient that you're able to do what was asked efficiently and with grace under pressure? Would you pretend you're still busy with something? One thing I've learned from my previous employer was that the way you do your work is something that people don't give a shit about. It's the outcome that matters most. Whether you're relaxed or stressed it's something people should not care about.