>>859584 (OP)
I don't understand what you're asking.
KDE is, and will always be bloated, because it's trying to be a "complete" desktop operating system with absolutely everything you'd ever need. It's great if you want something comparable to popular commertial OSs.
As for memory leaks, I don't know, but then again, I've never been able to tell. What I do know is that you won't gain anything by running old, unsupported versions. Just run the latest and report whatever bugs you find.