Looking at the release notes for Deepin Linux 15.10 (yes, I know it's not Manjaro, but it does contain Manjaro's desktop environment) I came across a very interesting sentence:
One of the most significant changes is dde-kwin is now the default window manager. Users should experience improved performance as a result.
I haven't had too many bad experiences with DDE's usual window manager (which as I understand is some version of Mutter) but decided to try it on Manjaro. I fired up Add/Remove Software, searched for dde-kwin, no dice. Does Manjaro have a different name for it?
I did find "deepin-kwin", but all that did was cause a whole lot of screen tearing. And the Terminal window doesn't blur anymore (it's a bit distracting if it's transparent with no blur).