The end result is a QFileInfo constructed from the QFileSystemEntry; QFileSystemEntry's API will at some point convert the NativePath (QBA on Unix) to a QString, e.g. when it calls findLastSeparator(). So instead of converting the parent dir path from Utf8 to Utf16 multiple times, store the dir path as a QString once in the constructor. Use QStringDecoder to convert the dirent->d_name to Utf16 and check the decoder's hasError(); which as Thiago pointed out, is more efficient than using isValidUtf8(), throwing away the results, then converting to unicode anyway later on in QDirIteratorPrivate::advance(). (Ironically) `QFileSystemEntry::NativePath nativePath` is still used on Windows. Change-Id: Icd2b130103640b502862d210d64926b99c499a01 Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>