Code Critic rule Optimization > String concatenation instead of streams says: "Check for string concatenation inside some iteration message. Since string concatenation is O(n^2), it is better to use streaming since it is O(n) - assuming that n is large enough. As a general principal avoid , since the receiver is copied. Therefore chaining , messages will lead to multiple useless copies of the receiver." That is, String streamContents: [:s | #('abc' 'def' 'ghi') do: [:each | s nextPutAll: each asString]] should be used instead of... 'abc' , 'def' , 'ghi'. However the first clutters the code. What about something like... { 'abc' . 'def' . 'ghi' } asStreamString where Collection>>asStreamString ^ String streamContents: [:s | self do: [:each | s nextPutAll: each asString]] cheers -ben