Lol KDE has many flaws but bloat isn't one of them, I get the feeling sometimes that the presence of several ultra-ultra-light "desktop environments" on Linux causes people to think the major ones are "bloated" when in fact they're much smaller than the DEs on Windows/OS X. FWIW "slow under certain circumstances" does not necessarily imply bloat b/c a single badly implemented feature can cause slowness but that's not the same as bloat; try enabling compositing in some old versions of Xfce (basically right after it was added, maybe Xfce 4.2?) and you'll see what I mean real quick.
It is a matter of taste, of course, but compared to Windows 8 and Windows 10, common Linux/Unix desktop environments like MATE or Xfce are very pleasant to use.
