Having tried to test the Plasma 5 desktop on many different machines I soon got very frustrated. On traditional i686 / Pentium 4 based systems plasma5 simply hangs producing a black screen. Even on newer hardware as my UHD-ready Core 2 Quad notebook with an NVIDIA Corporation G96GLM [Quadro FX 770M] it is largely unusable producing weird screen distortions. Finally on a relatively new intel Atombook Plasma 5 did run but was extremely slow until I disabled all desktop effects. That even though plasma5 was initially advertised to be less resource intense than plasma4 (However quite the opposite is true).
  My request would be to simply check hardware requirements at startup and exit if they are not met. That would safe unsuspecting users from frustration and testers from huge amounts of lost time. I remember it was like this for Plasma 4 which did output on a Pentium 3 system to the console that it requires SSE2 and thus a Pentium 4.

Reproducible: Always