So because of my streaming setup there is about a 1 second delay between what the timer does and the gameplay. I use the auto-splitter so the beginning should be exact, however at the end I split right as the gameplay shows the mission passed screen so I hope its OK. As a result I think about 1 second will be added to all of my runs while I use this setup, but I am nowhere close to competitive enough for that to matter to me in my runs so I am not worried about it.