Hi @SM123 

Please send us the result of these steps:
 

It might be a performance issue
Please provide the following info:
 
1.  How many items are in your 'NintexWorkflowHistory' lists?  (should be under 5,000 items)
Navigate to Http://SiteName/Lists/NintexWorkflowHistory and check how many items are present.
or 
go to Site Settings --> find a Nintex Workflow group -->click on the "Manage workflow history lists" link
 
2.  How many workflow tasks are in the Task List this workflow utilizes?  (should be under 5,000 items)
Navigate to the task list your workflow/task action is configured to use and check how many items are present

3.  How many rows are in your 'dbo.WorkflowProgress' table in your Nintex Workflow databases (SQL)?  
 
5.  Also, please create a and run a simple workflow test on the same SiteCollection : and provide us with the result.
- using Nintex workflow : START -> Log history -> Pause 5 min -> Log history -> END     save/publish and run, does it run and complete within 5 min?
- using SharePoint Designer workflow (SPD) : START -> Log history -> Pause 5 min -> Log history -> END     save/publish and run, does it run and complete within 5 min?

Also, would you be able to check How many items are in the SharePoint table ScheduledWorkItems] ? this table should be in the SharePoint content DB.
 it might be that the SPTimer job is so busy processing this job queue when it comes to processing a workflow with Pause action.

Thanks,Majid
  

Hi @SM123 
Have you resolved your issue?

Hi Majid,

How do you clean up the NintexWorkflowHistory lists and workflow task lists if they are well over 5,000 items?

Thanks,

Jamie

Hi Jamie @SM123 

regarding the Nintex history list please follow these steps : 

for workflow Task List : please follow these steps : 

As best practice: if you believe your workflow design would create too many History List items and too many Tasks, its best practice for that specific workflow to have its own history and task list as following :

New Task for specific workflow : 

New History List : https://help.nintex.com/en-us/nintex2013/help/workflow/RootCategory/SharePoint/Nintex.Workflow.ManageHistoryLists.htm

hope that help,
Majid