Did you give Plasma a try recently? It's featureful, configurable, maintained, and lightweight (even more than the newest XFCE to the surprise of many).

I've been running KDE since I set up my computer to work from home back in February. I don't have the latest hardware, since I mostly built it from parts I had lying around, but it's not bottom of the barrel. 8-core AMD FX-8350, 20GB of DDR3, GeForce GT 720.

One problem I've had with KDE is that after running it for a few hours, it would get really really slow. It was so slow that I could actually watch the title bar redraw when I would switch windows. Turns out that a 1GB graphics card isn't enough to do compositing at 4K when you have more than a few windows on the screen. Fair enough.

So I turn off hardware compositing in firefox, chrome, and plasma. I boot the computer, and check memory usage in nvidia-settings. With just plasma running and a few docked widgets, I've already used 342/978MB. Perhaps the widgets are at fault, but I'm pretty I was able to run fvwm and gkrellm on my S3 Virge back in the day, and it had far less than 1GB of video memory.

I also notice that sometimes I lock my computer for the night, then I come back in the morning to login, and the hard disk churns for minutes before I can type my password. I never had this problem with xscreensaver. There's plenty of RAM available. I know my 5400rpm RAID 1 setup isn't the fastest, but this is absurd.

Then there's the K gear menu. Why is it so slow? I click the icon, go to Applications, then go to Utilities. Then I wait a few seconds. Eventually they all show up. Then I go back to All Applications. The menu stalls for a few seconds. What is it doing? I don't know. The fluxbox menu never stalled like this.

The default picture viewer seems to be gwenview. I've imported a bunch of pictures from my phone and they are stored on my HDD. I double-click on an image, and then I want. And I wait. And I wait. No indication that it's doing anything; maybe my double-click didn't register. So I double-click again. I wait some more, and suddenly I see two gwenview windows. After a few seconds neither one has fully initialized the UI or loaded the image. I close one of them, wait some more, and eventually the image shows up. Why is it so slow? I don't remember images loading this slow in xv or eog. Should I be using digikam? I just used the default.

The apps in the system tray are terribly slow. Let's say I want to change my volume while a video is playing. That should be simple enough. So I click on the volume control. I wait for it to show up. Then I drag the volume slider. It is slow enough to respond that I overshoot. Oops, too low. Bring it back up again. Overshoot again. I really need to set up some volume up/down key bindings so I don't have to mess with that thing. Oh, and my headphone volume always starts out muted after I boot the computer. No idea why. The slider doesn't show up in KDE, but I can adjust it just fine in alsamixer. I blame pulseaudio. If I were young and without kids I might have time to figure out how to go back to OSS. I remember when sound was as simple as running sndconfig and then listening to that wonderful voice say, "Hello, my name is Linus Torvalds, and I pronounce Linux, 'Linux'". The good old days. Life was simple.