In the CMS plugin, the migration script file org.ametys.plugins.cms.upgrade/v20201030T000000-CMS-10565.js must be optimized. Indeed, when you have a lot of complex contents with multiple concerned fields, it can take a very very long time to execute.

Also, add logs to inform the user.

Ways to optimize:

• Get all richtext in repeater attributes path from the model before iterating on contents with the content type - Then explore contents in details only on these paths
• Prepare the SAX Factory only once and call saxFactory.newTransformer() each time you use it
• Close the StringReader
• Before applying the XSL, maybe we can detect the word local into the rich-text but I'm not sure it works well