The Performance Impact of Using dict() Instead of {} in CPython 2.7knowledge-baseAug 24, 2026By Team M37Labsdoughellmann.com/posts/the-performance-impact-of-using-dict-instead-of-in-cpython-2-7-2Doug HellmannThe Performance Impact of Using dict() Instead of {} in CPython 2.7I’ve been reviewing lot of code lately for various open source and internal projects written in Python. As part of those reviews, I have noticed what I think is a trend toward using dict() instead of {} to create dictionaries. I don’t know exactly why this trend has emerged. Perhaps the authors perceive dict() as more readable than {}. Whatever the reason, my intuition told me calling the function version of the constructor for a dictionary would impose a performance penalty.doughellmann.com
