Certainly it is a productivity killer when a developer is constantly interrupted by other workers, bosses, etc - but it is even worse when the developer is constantly interrupted by his or her own tools and equipment.
For example, if a developer must wait 10 minutes for each build he makes - so that he can iteratively test code he is working on, the effect on productivity is devastating. Or perhaps the build is fast, but copying the bits to a test VM takes 3 minutes. Once again, the developer is being vexed by a lack of "responsiveness" in the tools and procedures being followed.
I believe there is a name for an environmnent that is free of these problems, or perhaps a name that is plagued with these process and tool interruptions. I can't recall the name or industry "label" for this. Anyone recall?