I performed a simple update item permission update using Nintex workflow. It is very slow and unreliable. Is it any way that It can be optimised?  

Test Steps: 

1- Created a simple list with 2 columns.

2- Created a workflow to update item permission (Break Inheritance and set Unique permission)

3- logged each step 

4- created a new item 

5- took 2 - 3 minutes to complete the item permission update. 

6- Steps are logged in the workflow history 

7- Create a loop to perform this operation 10 times 

8- After seven attempts and a very long wait for each step, Workflow failed to set permission

Is it any way that it can be optimised and make the workflow run faster?