Hi, Based on feedback by Norbert Hartl, Stuart Herring and Dale Hendrichs (thank you) I improved the current STON version a bit. http://ss3.gemstone.com/ss/STON https://github.com/svenvc/ston Changelog: A nasty cycle bug was fixed Performance was improved, especially for large structures. Some implementation changes (recursion done using a stack, stonProcessSubObjects: optimized using stonContainsSubObjects) I did some stress/performance testing/tuning. Using STONTestMap classTreeExtended. to generate a structure mimicing the class hierarchy, with objects for all classes, about 7000 in my image and all methods, about 64000 in my image, with super/subclass and method owner links to create cycles. This results in a 7 Mb .ston file. The normal code, serializes this in 28 seconds and materializes it in 11.5 seconds. The 'fast' versions (using ZnBuffered[Write|Read]Streams and Fuel Large Datastructures) does it in 1.1 and 3.8 seconds respectively. New users are always welcome. Sven -- Sven Van Caekenberghe http://stfx.eu Smalltalk is the Red Pill