I second the suggestion to use OrcaSlicer from SoftFever. If you want to go faster you need it.
If you’re not using I wrote a long a$$ PSA (Public Service Announcement, not as fun a WAG) about it and BL Studio as well as Arachne, another commonly misunderstood item:
https://forum.bambulab.com/t/psa-up-your-game-studio-softfever-orcaslicer-arachne
OrcaSlicer has several Calibrations that will let you max out and fine tune your printer for a .8 nozzle. He put them in proper order on the Calibrations tab at top. Don’t forget to look at his Wiki which explains how to use them, with pictures, it’s in my post.
I usually run a .6 and found after calibrations tests that I could run the Max Volumetric Flow almost three times the default value for PC (polycarbonate) and it tuned other settings for beautiful smooth surfaces as well.
Don’t forget the rule of speed: If you increase speed you must step up the nozzle temp too to help melt the plastic faster and get good layer adhesion. Which means you also must up the fans to cool it for each layer. This stuff gets complex quick! 
That can all be saved as a Filament Profile for future one click access. I name it like this:
Polylite PC Red .6 with the nozzle size so I remember which profile is which.
One other thing to consider. If you really have a need for speed, look into replacing your nozzle with a high flow version called CHT. There’s a long discussion with links here:
https://forum.bambulab.com/t/first-benchy-printed-with-bambu-lab-x1-cht-nozzle
Cheers!