For the Fastest Slayer Experience in Old School, you'll be extending burstable tasks with Slayer Points and the Bracelet of Slaughter.
Then you'll be using the Expeditious Bracelet and a cannon on tasks that aren't burstable.
Then you'll skip and block the absolute slowest tasks, regardless of how profitable they are.
Duradel is the best master to use for the fastest experience.
And next is Nieve or Steve.
You should not use Konar if you're going for the fastest XP.
These are the tasks that you should skip.
All of these tasks are not cannonable and slow.
In terms of tasks you should block, it depends on the task weightings, which means how often they get assigned.
On the screen, I have the suggested blocks for Duradel and Nieve, taking into account their task weightings.
With your Slayer Points, this is the unlock order that you should use.
You should always start with Bigger and Badder for the extra Slayer XP, then block tasks, extend Dust Devils and Necroyals, then unlock the Slayer Helmet and Slayer Rings.
As I mentioned, you should always be using the Bracelet of Slaughter on burstable tasks, and you should always use the Expeditious Bracelet on any other task that you do.