Hi all, I am playing with MessageTally, and I have a strange result with prealocation. Here is my example. I am working on a PharoCore1.3, with a VM4.2.5 First of all, I spy this source code: ==== MessageTally spyOn: [ 500 timesRepeat: [ | str | str := ''. 9000 timesRepeat: [ str := str, 'A' ]]]. ==== The result appears after 24 961 ms. An optimization is to use a Stream. Here is my source code: === MessageTally spyOn: [ 500 timesRepeat: [ | str | str := WriteStream on: (String new). 9000 timesRepeat: [ str nextPut: $A ]]]. === The result appears after 812 ms, which is a large improvement. Now, we could optimize again using the preallocation. Here is my source code: ==== MessageTally spyOn: [ 500 timesRepeat: [ | str | str := WriteStream on: (String new: 10000). 9000 timesRepeat: [ str nextPutAll: 'A' ]]]. ==== And the result is strange: it makes 2 times slower to display the result. The result appears after 1656 ms. Here is the spy result: === - 1656 tallies, 1656 msec. **Tree** -------------------------------- Process: (40s) 464519168: nil -------------------------------- **Leaves** 22.9% {380ms} UndefinedObject>>DoIt 22.5% {373ms} SmallInteger(Integer)>>timesRepeat: 22.2% {368ms} WriteStream>>nextPutAll: === There is the call of UndefinedObject>>DoIt which is added and takes time. Does anyone know what is done during the preallocation ? Why is it slower than non-preallocation ? Thanks for your answers. Jannik