One of the most damning indictments of current software architecture is the laggy mouse which we've all gotten used to on mainstream OS.
The other day my son and I were sitting in front of the XBOX ONE we (try to) use as a Plex client and laughing about how showing a new logo while the machine is doing something meaningless to us is an act of brand destruction and that they should be showing us a Playstation logo instead... And how with the NES you could just hit the power button and start playing. The cursor never lagged like that on the 1984 Mac.
Its also one of the most immediately visible degradations of user experience. The cursor is your agent to interact with the computer, an extension of your arm basically. It should be one of the most smooth and responsive pieces of an OS.
I remember a long time ago, early days of Gnome 3 when doing large file operations would hang the cursor. It made the whole system feel like complete garbage, totally unacceptable.
A cursor lagging (or any kind of GUI/user interaction stutters) should be a critical high priority bug, all hands on deck sort of thing. The entire experience of using the damn thing hinges on the responsiveness of the interface and pointing devices.