XQuery V8.0.1 versus V4.4.1

We have recently upgraded from tamino V4.4.1 to V8.0.1.
When we were developing the system in with V4.4.1 we spent quite a lot of time tuning our queries to be as fast as possible.
Now having moved to V8.0.1 we have noticed that some of them run slower than on V4.4.1. This could be a large amount of work for us to go through and tune the queries again.
Has anyone else noticed this ?
Is this a known problem ?
Have the criteria for tuning queries changed ?
I check the documentation but it looked like the section on tuning queries had not changed since V4.4.1.


I asked a tangential question and the advice was to open a support request for any specific cases where queries are slower in v8 than in v4.4. There shouldn’t be any slowdowns.

There was no major rewrite of the query optimizer between these versions, however individual optimization rules may have been modified. When facing a slowdown, this may be caused by some rules not working as good as before for a given situation, or some other bug. I would second the recommendation for opening a support request to have this inspected. Ideally, supply the schema and an “explain” output of the query.