TYPO3 Core

The FAL indexer currently regards all files as changed, since value and type are checked in detectChangedFilesInStorage():

                ...
                if ($indexRecord['modification_date'] !== $modificationTime['mtime'] || $indexRecord['missing']) {
                    $this->filesToUpdate[$fileIdentifier] = $indexRecord;
                }
                ...

The modification date returned by SplFileInfo is an integer but the modification_date in the index record is a string, so all files get updated

array(2 items)
   $indexRecord['modification_date'] => "1455633777" (10 chars)
   $modificationTime['mtime'] => 1455633777 (integer)