I would never forget to remove old .plg's. :D I was not aware of the fact that they brought patch 4.0 for EN Patch.
Testing out now if it works with 4.0 and speedfly.
EDIT: @Vermil Patch 4.0 installed, speedfly.plg as the only plugin and tested it now with 3.2,3.3 and 3.6. Exception (prefetch...