You might be greeted by this error message ‘Due to heavy load, the latest workflow operation has been queued. It will attempt to resume at a later time‘ sometimes when you check the status of a workflow. If there are many workflows trying to run at same time, SharePoint timer service has to push back some of those and queue them for processing later. Timer service does a lot of things behind screen in SharePoint. Timer service instance is installed and will be running on every SharePoint server in the farm. It’s duties include updating components of farm, running services, updating data and configuration and everything else SharePoint does! Running workflows is one of the many things it does. You see the above error if timer service is hit with many workflow instances which it cannot handle all at once.
There are some Farm level settings for workflow management which we can update to improve the overall workflow performance of workflows. But this might have some effect on other thing Timer Service does.
1. Increase Throttle Size: Working throttle size setting controls how many workflows can be processed at any time on entire server farm. Increasing the throttle time, will increase the number of workflows running at any time in the server farm.
2. Increase Batch size: Workflow batch size property controls the number of items waiting in queue to be processed by timer service in every run.By increasing the batch size, more number of workflows can be queue to be processed at a time.
How to Check existing Workflow settings:
How to update workflow Batch size: