Coming from former RARE dev, Martin Hollis...
I wrote a piece of code which displayed spinning icosahedrons; as many as possible until the framerate dropped below 60Hz. The head of the project at SGI was not too pleased to discover what the performance of the machine was in terms of triangles per second. He asked to see my code in the hope it was inefficient. It wasn't. He later told me that SGI very nearly did another spin of the hardware to fix the issue, which was with the memory interface. I don't know exact figures but a second spin of the hardware (equivalent to a second edition of a book) is sometimes said to cost a million dollars, and there is the additional cost of a delay in reaching the market which might be enormously larger.
I remember the initial N64 delay very well. Still brings a tear to my eye to this day. Now imagine how much worse things would have been if this issue were acted upon!