Plasma 5 pushes QtQuick to the limits. It sounds like a cheesy marketing line, but it's true. Unfortunately this isn't a good thing. Although Plasma 5.1 is somewhat stable we have had some crashers, and whilst we've worked hard to fix the ones that are ours a sizeable number of these were caused by problems deep inside Qt.
Fortunately Qt 5.4 has just been released. It contains countless bug fixes that really improve the situation; several of which were even written by me and the rest of the Plasma crew.
We need people with Qt 5.4 (hey all you Arch people) to help go through all open crash reports and test if they still happen since upgrading.
I don't like closing bugs wtih a vague "it seems to work for me" without getting at least a second opinion, I may be overlook something and it's not fair on the original reporter.
I've added a quick link to the high priority candidates
And feel free to help go through the rest of our list
So far everything is looking very positive towards having a completely rock solid Plasma 5.2 in January; lets make it happen.