Prior to Houdini 21, when ever you installed an HDA to your hip, `hou.hda.installFile()`, it would internally run the `dsreload` hscript command which rebuilt all the shelves and toolbars. Which for one HDA isn’t expensive. But this would happen for every HDA installed, and the more HDAs you installed the longer it would take. So they added a hou.hda.installFiles() as a way to batch it, which triggers a single `dsreload` at the very end. Internally when loading a hip the same thing would happen, so they changed the hip file loading to batch load them as well.