196
Python Performance: Why 'if not list' is 2x Faster Than Using len()
(blog.codingconfessions.com)
this post was submitted on 12 Apr 2025
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Technology
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It comes down to the question "Is YOUR C++ code faster than Python?" (and of course the reverse).
I've built a SCADA from scratch and performance requirements are low to begin with, seeing as it's all network bound and real world objects take time to react, but I'm finding everything is very timely.
A colleague used SQLAlchemy for a similar task and got abysmal performance. No wonder, it's constantly querying the DB for single results.
Exactly!
We rewrote some Fortran code (known for fast perf) into Python and the net result was faster. Why? They used
bubble sortin a hot loop, whereas we used Python's built-in sort (probably qsort or similar). So despite Python being "slower" on average, good architecture matters a lot more.And your Python code doesn't have to be 100% Python, you can write performance-critical code in something else, like C++ or Rust. This is very common, and it's why popular Python libraries like numpy and scipy are written in a more performant language with a Python wrapper.