I think it's file manager in particular. When I need to do something muscular I open a DOS box and just do it at the command line. It feels plenty zippy though I haven't bothered to do any benchmarks; I have to confess I've never learned Powershell because it's so easy to get most things done with command.com.

Although Windows remains my favorite environment I share the annoyance at how MS really polishes some things while failing on basic functionality, when they definitely have the resources and skills to fix that. Every time my wifi or WAN hiccups I wonder why Windows still lacks decent network history/QOS tools out of the box.