The efficiency of FileList>>listForPattern: is something which should deserve a bit more care. It tries to sort the files, for example by name, but wants to display directory first ^ [ :x :y | |xIsDir| ((xIsDir := x isDirectory) = y isDirectory) ifTrue: [ x basename <= y basename ] ifFalse: [ "directories always precede files" xIsDir ]] Alas, this isDirectory test cost you an arm: FileReference>>isDirectory ^ filesystem isDirectory: path FileSystem>>isDirectory: aResolvable "Resolve the argument, and answer true if the result refers to a directory, false if it refers to a file or doesn't exist." ^ store isDirectory: (self resolve: aResolvable) FileSystemStore>>isDirectory: aPath aPath isRoot ifTrue: [ ^ true ]. self nodeAt: aPath ifPresent: [ :entry | ^ self basicIsDirectory: entry ] ifAbsent: [ ^ false ]. DiskStore>>nodeAt: aPath ifPresent: presentBlock ifAbsent: absentBlock | name| aPath isRoot ifTrue: [ ^ presentBlock value: self rootNode ]. "| encodedPath encodedBasename entry | encodedPath := Primitives encode: (self stringFromPath: aPath parent). encodedBasename := Primitives encode: aPath basename. entry := Primitives lookupDirectory: encodedPath filename: encodedBasename. ^ entry == #badDirectoryPath ifTrue: absentBlock ifFalse: [ entry at: 1 put: aPath basename. presentBlock value: entry ]." name := aPath basename. self directoryAt: aPath parent ifAbsent: absentBlock nodesDo: [ :entry | (self filename: (entry at: 1) matches: name) ifTrue: [ ^ presentBlock value: entry ] ]. ^ absentBlock value Arghh, it scans the whole parent directory again! If sort is O(n log n), then we transform it into O(2 n^2 log n). Try to browse your package-cache if you're not a chicken. Seriously, it's unusable... Nicolas