As most of our products can be used from a SharePoint workflow, it is perhaps useful to know how to tweak SharePoint’s workflow engine for high-load or other specific scenarios.
This article explains in detail what can be tuned and how it can be tuned. If you are in a rush then you can skip over the first 20%.
Workflow Throttle: Controls how many workflows can be processing at any one time on the entire server farm. This setting does not control how many workflows can be "In Progress" concurrently, but rather how many can be actively using the processor. When this number is exceeded, workflow instances that are started and events that wake up dehydrated workflows are queued for later processing. The default value is 15. This setting is per farm, so the number of front-end Web servers is irrelevant
stsadm -o setproperty -pn workflow-eventdelivery-throttle -pv "25"
Workflow Batch Size: Workflows, by their very nature, do not execute in a nonstop, linear fashion. Instead, they run for a little while, pause, run some more, and then pause again, continuing in this manner until the process is complete. Although an outside observer or a developer might disagree, workflows are a collection of batches and the workflow engine is simply a glorified batch controller.
stsadm -o setproperty -pn workitem-eventdelivery-batchsize -pv "125"
Workflow Timeout: The timeout setting specifies the amount of time (in minutes) in which a workflow timer job must complete before it is considered to have stopped responding and is forced to stop processing. Jobs that time out are returned to the queue to be reprocessed later. The default timeout period is five minutes
stsadm -o setproperty -pn workflow-eventdelivery-timeout -pv "10"
Workflow Timer Interval: The workflow timer interval specifies how often the workflow SPTimer job fires to process pending workflow tasks. This interval also represents the granularity of delay timers within your workflow. If a timer is set to delay for one minute, but the interval timer fires only every five minutes, the workflow delays for five minutes, not one minute
stsadm -o setproperty -pn job-workflow -pv value -url http://myWssServer
For our products you may need to tweak Workflow Timeout for very long running PDF Conversions. Changing the Timer Interval can be useful during development when using Pause Until or Pause For workflow Activities.