Imo the new task manager is much better. I used to use Process Explorer instead of the old (so called classic) task manager, but I don't bother with it much anymore (well, it also doesn't work great with nVDA, to be fair...)
I did notice that there were huge and annoying lag for my screen-readers (never tried narrator though) with both task manager and settings apps...I mean, having to wait five or six seconds between a key press and speech output. Thankfully this "went away' several windows updates back, though I'm not really sure when.