Hi! Frank sais: "Traditionally Smalltalk has one Object-Memory which is garbage-collected. This introduces overhead and complicates things in multihreading programs. LSWVST introduces multiple Object-Spaces, in which garbage collection can be controlled by the programmer. Every thread has its own Standard-Object-Memory avoiding synchronisation problems. Traditionally in Smalltalk every object is boxed. An object is a pointer which has a reference to the class. This is necessary to dynamically lookup the method during resolving a message-send. This makes programs which operate on huge data-collections of the same type rather inefficient. LSWVST introduces a new object-type - IsoCollections. Iso-Collections stores type information of its elements only once." Hmmm, opening a simple Array of 1.000.000 elements consumes 4 megabytes in Pharo ... regards, Guido Stepken