Well, this is latin1-centric, but could speed-up a majority of us, since most code is written in English. The idea is to use Andreas fast conversions ByteString>>#squeakToUtf8 ... However creating an intermediary Stream then an intermediary String is not necessary... So we'll have to replace this with dispatching techniques. Moreover, the technique can be generalized to other encodings. More more over, the lineEndConventions can be handled by the very same trick. To achieve this, we install a latin1Map and latin1Encodings as class instance variables in TextConverter to generalize Andreas' squeakToUtf8 trick. Then we copy these in instance variables. This is to enable lineEndConventions mapping. Then we care to #installLineEndConventionInConverter in MultiByteFileStream to initialize TextConverter variables. Then we use following dispatching: MultiByteFileStream nextPutAll: -> TextConverter nextPutAll: And use a hack for ByteString in TextConverter nextPutAll: (dispatching on String would be overkill by now). To measure how it can enhance things, I put a hack in Debugger class>>#openOn:context:label:contents:fullView: Preferences logDebuggerStackToFile ifTrue: [MessageTally spyOn: [Smalltalk logError: title inContext: context to: 'SqueakDebug.log']] Then did a 0/0 FasterLatin1Conversion reduce tallies from - 11452 tallies, 11586 msec. to - 3625 tallies, 3718 msec. Still a little bit long for a Debugger to open, but already better. Nicolas