String concatenation vs. string substitution in Python

Question

In Python, the where and when of using string concatenation versus string substitution eludes me. As the string concatenation has seen large boosts in performance, is this (

Answer 1

"As the string concatenation has seen large boosts in performance..."

If performance matters, this is good to know.

However, performance problems I've seen have never come down to string operations. I've generally gotten in trouble with I/O, sorting and O(n²) operations being the bottlenecks.

Until string operations are the performance limiters, I'll stick with things that are obvious. Mostly, that's substitution when it's one line or less, concatenation when it makes sense, and a template tool (like Mako) when it's large.