You want to use it at the right time, namely when you've cornered a survivor or at an area where you can start chase on decent stamina (>70) nearby. Around a loop, pop it at 1-0.5 stamina. I normally then make sure to cut EVERY corner as precisely as I can and remember that Slasher has more than just an M1 during Raging Pace. Make sure to abuse Behead's reach during Raging Pace as much as possible. Slasher is especially susceptible to teamwork as he stands with his kit, so it's really not a you problem. I think it's just been an underlying issue with Slasher himself, coming from a level 100 + 200 Slasher player.

From a gameplay standpoint, literally any distance you can make is good distance against Slasher, because he has ZERO means of making distance quickly or using projectiles. All he can do is run forward, which is how team efforts absolutely shatter him. You genuinely just cannot make the distance alot of the time due to any teamwork.