So, you want to go fast? Well, you need to avoid obstacles or slowdowns of course, but the more interesting thing to talk about is how to increase speed. There are three main ways to increase your speed beyond what simply sprinting does.

Simple and easy to observe. The wall run isn't particularly fast, but when you jump off, you get a significant boost of velocity in the direction you're facing. The angle is also affected by left and right inputs. This boost can be stacked, so in the event you have many wallrun locations in a sequence, you can keep jumping quickly against each surface to keep building up speed. In areas like the start of Parkour 3, it may be worth using a wall jump to build speed quickly, even if it wouldn't be otherwise required. Remember that we typically want maximum horizontal velocity, so don't look up more than you have to in most cases.

While rare that a parkour level gives you a grapple point, they have the greatest potential to build immense speed. Your goal should be to start grappling as far away as possible to give yourself the biggest amount of potential energy, and then release from the swing when you have maximized your horizontal velocity and are not moving up too much. Think jumping off a swing on a playground. You don't get many of these opportunities, so make the most of your speed and try to maintain it as much as possible.

Yep, while it isn't super obvious, the kick actually can increase velocity in the direction you face. I've just been calling this "Kick Tech". The velocity gained from kicks may not be that high, but with the only limit being the kick cooldown, you'd be wise to make use of kicks pretty much constantly. This is especially strong if you use it while already using one of the other two main ways. If you jump off a wall and have a kick ready, you should pretty much always use it. I haven't really gotten Kick Tech down to an exact science, but once you get a feel for it you can incorporate it into your parkour moves constantly.
Further experimentation is required to see if it actually matters, but sometimes charging a kick during a big jump SEEMS to make you go faster, but this may well be an illusion. https://youtu.be/g18Jty_b958
The thing that can make Kick Tech really great is if you can preserve momentum well and keep adding more kicks, so how do you preserve momentum?

(Steam refuses to display my videos if I insert them directly.) https://youtu.be/iUmkYEZbXuE

Aside from Kick Tech, you basically experience the velocity boosts naturally as you proceed through a parkour level, but what's really important is carrying that speed beyond that point. You actually don't lose momentum that quickly while simply running, it seems to drop off a little slowly, so you actually have pretty good leeway.

Maximize air time when you are already going fast. Wallrunning or normal running will cut your speed, but flying through the air/jumping will minimize this loss.

B-hopping is a common game mechanic for preserving momentum, you see it in games such as CS:GO, Half-Life, and Mirror's Edge. If you've never heard of it, it's basically just jumping at whatever frame you hit the ground. Now, as far as I can tell, the b-hopping in this game is pretty simple physics-wise. It's just maximizing air time again. Unlike in the games I mentioned, you will still touch the ground and lose some momentum, that seems pretty impossible to avoid, but by jumping constantly, you stay in the air longer. Staying in the air longer makes you lose your momentum slower. Do this in tandem with kicks and you can start chaining kicks together even without other boosts at play. There are not many places in the game for this, but parkour 3 and 4 have a lot of long, straight platforms which can allow for Kick Tech chaining.

The faster you are already going, the faster you should be jumping off of walls, and as always, keep kicking. For the same reasons we b-hop on the ground, we don't want to spend too long running on the wall, because we'll lose momentum.

Heya, I'm CatQueen13. I'm one of the ~3 people few people to have speedran this game, and also happen to be the one who created the leaderboard on Speedrun.com. There may not be an timer ingame for parkour levels due to the checkpoint system, but going fast on the parkour levels is very satisfying and in my opinion, is a big part of what makes this game such a treasure trove of a speed game. In making this guide, I was hoping to get some other players interested in speedrunning for Diatomic. Also because I noticed a majority of people I know simply do not use Kick Tech.

While the theory is laid out here, I'm not very good at executing it yet, and considering that right now there isn't any competition for parkour runs, I've got no reason to improve. Now I do :)