"We should forget about small efficiencies, say about 97% of the time: premature optimization is the root of all evil. Yet we should not pass up our opportunities in that critical 3%."
The sense of the quote is that you should avoid writing obfuscated, unreadable, and error-prone code in order to gain an insignificant performance advantage, because the most important performance gain will be achieved only in 3 percent of your code. However, you should take precautions to not lose the opportunity to improve performance in that critical percentage.
In this section, we will talk about those precautions; we will see some general rules to avoid well-known performance issues with Cypher. If you follow all of them, you will reduce the probability of facing poor performances in your applications without affecting the readability of your Cypher queries.