How to troubleshoot when a customer complains the data steward application is very slow - including taking more than 10 seconds to open a BOV, taking more than 1 minute to check out records in a duplicate management workflow, etc.

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1. Under Preferences → Data Stewardship, uncheck Predictable Pagination. 
2. Open the BOV. Under More, look at Customized Sort. Are there any attributes sorted? If yes, remove all attributes. This should increase speed of application. The more attributes sorted, the longer the BOV will take because Oracle is taking a very long time to sort the attributes when the BOV opens.
3. No attributes under customized sort? What about Customized Sort defined in the Workbench under the BOV configuration? If Customized Sort is turned on and there's a sort expression, turn off Customized Sort and performance should be improved. 
4. If there's still bad performance or NPE when opening BOVs, sort preferences might have a problem. Go to Preferences, Under Filters restore defaults. Under Sort Criteria, also restore to defaults. Getting rid of Sort and sort preferences usually solves the problem. What can happen is a user who is waiting a long time for a BOV to open can get impatient and click the refresh button on the browser. This causes the preferences to get in a weird place and resetting them should fix any exceptions.

Dupes Mgmt Workflow takes a long time 

Step 1: Troubleshooting in Semarchy

1. Check there is no Customized Sort

2. Under display settings, uncheck Autofit columns, Colorize consolidated Master values, Colors Golden IDs.

3. Checkout 33K records check out take a very long time.

4. Best practice: Should not have check out more than 1K records in basket for dupes mgmt. Tweak match rules to do autoconfirm . Apply filter to check out golden records with less than 7 master records. Why golden records that have master counts of more than 7 get checked out as well? Because the attached golden records also impacted that might have more than 7 master records are check out together in basketif a data steward is checking out more than 1K records to blindly confirm them.

5. Good idea to remove records from basket. Don’t just cancel out of workflows. Probably doesn’t help performance to have . Actually Select All and hit Delete. If you only cancel out of workflows and do not actually delete the records, you end up having huge amounts of data in UG and UM tables. Probably hurts performance. Can  Can write a script to prune the UG and UM tables.

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DE workflow takes a long time to finish processing integration job

Probably have Calculate statistics turned on. Check out this article for details.