In an article I see this phrase "Faustian bargain". Both I and my teacher were unable to translate or understand it. Can you help me and explain this phrase?

Context:

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> The reason for linking all the modules together in a single address space, with no protection between the modules, is that designers have made a **Faustian bargain**: better performance at the cost of more system crashes. We will quantitatively examine the price of this trade-off below.
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This comes from the first page of this work: <http://docs.huihoo.com/minix/reliable-os.pdf> or <http://74.125.155.132/scholar?q=cache:_sabEZ3IFvsJ:scholar.google.com/&hl=en&as_sdt=0,5> (preloaded as google html view)