Hi, as I didn't remember the name of the tool and maybe as future reference to myself. I have installed RefsHunter from the catalogue and it helped me a lot. I was looking at the memory consumption of my Pharo6.0 image and did something crazy like counting how many objects exist of a specific class (Object allSubInstances copy do.. and put that into a dictionary). I noticed that for the ASN1 model the nodes of the parse tree survived. Yesterday I tried to use the pointer explorer but then most references are held by the UI code and I gave up after a bit. Today I found the RefsHunter again and something as simple (found through the class comments) | rh | rh := RefsHunter snapshot. rh wayFrom: ASN1AssignmentNode allInstances first to: myAsn1Model Brings me to a list of references and when searching the list from the end to the beginning gives a pretty good picture of where things go wrong. Great to have a platform that allows to walk the heap and great that there are tools that make it manageable! have a nice weekend holger