nicmar We decided to go for another solution where we add a mesh to head and hair, and then modify that with an animation, if the hat is worn. That should also be more performant than using clipping anyways, right?
Glad to hear you've got a workaround in place, thanks for sharing! Yes, avoiding clipping attachments is generally advised wherever possible.
If at a later stage the stress level is lower and you have some spare time and can reproduce the memory-leak with a minimal project, we would be happy to fix the issue where possible of course. We fully understand however that you have more pressing tasks to attend to at the moment.