To time all speedruns we use a program called LiveSplit. Download it by clicking the latest version, extract the zip file wherever you want (to your desktop is recommended), and open LiveSplit.exe. We generally divide the runs (or) segment(s) into Splits. Splits are basically parts of the whole run. Splits allow you to track your time on each segment or "Mission Part/Sequence" in this case, and see by how much your are ahead of your PB / Personal Best when running the game. You can find the splits we use here, in the Splits section of the Resources tab.

Generally most games have something called an autosplitter, basically it will split automatically once you load into or finish a mission/level. Unfortunately PCBS2 does not have one yet It's Suggested that you go into your LiveSplit settings by right clicking LiveSplit -> Settings, and turning on global hotkeys, this allows you to split manually in game or to undo splits without having to click on the LiveSplit program. While in settings you can also set your hotkeys for splitting, resetting, pausing, and undoing. Something to mention is that you cannot pause mid run or your run will be denied. All of our categories don't require Livesplit, as our mods manually retime each runs submitted, but it is suggested for you to make things easier for yourself. If you do not have 2 monitors, a settings I suggest is "Ignore Mouse While Running and Not In Focus". You'll find that by: right clicking Livesplit -> Edit Layout ->Layout Settings -> then at the very bottom you'll see it. This setting is important because it allows you to have Livesplit on screen while playing and it prevents you from accidentally clicking into Livesplit.