The consequences are really minimal, everytime e.g. a folder or blueprint view is entered for the first time, where preview renderings are needed, the compilation then takes place in the background, and the standard Default Material is shown in the meantime.
This is what S-ed explained here; the topic has sparked a bit of a discussion, I invite you to weigh in 
The setting of JobCacheDDC=1 is not working so well anymore in 5.1 though…