Check the following document where you can see how to create workflow models or edit existing workflow models:Creating Workflow Models

Check this repo ... its old but can help you to get what you are looking for:GitHub - viveksachdeva/elasticsearch-cq: Integration of ElasticSearch with CQ5

I  tested this scenario in AEM 6.4.4 and things work as expected... BTW, how do you change the URL when moving a page ? You are only asked for the new page tile/name and the location.

Can you force a recompilation of all Sling scripts jsps, java, and sightly and also invalidate cache per the following document of verify the behavior: How to force a recompilation of all Sling scripts jsps, java, and sightly in AEM 6.4

the following write up may help you:Limit tags selection to certian number in AEM 6.0 ~ T20mins

Are you saying by default the "error.log" was not getting created ?Can you see this logger in http://host:port/system/console/slinglog

Check Imaging Transcoding Library. This can be something that you need.

What if you set the log level to more verbose level e.g. debug ?

I suggest to take some thread dumps to understand what is causing the issue then base don the take the next steps to mitigate the issue. Please note that having concurrent requests should not cause any performance issues. Also check the following document that discusses common reasons for performanc...

You may want to take some thread dumps to understand what is causing the performance issue and then address it accordingly.