f-strings vs. str.format(): A Performance Comparison

While str.format() has been a mainstay in Python, f-strings have emerged as a powerful alternative. With the promise of conciseness and simplicity, developers may wonder if f-strings will eventually replace their predecessor.

Deprecation and Future Compatibility

Despite concerns about its deprecation, str.format() remains an integral part of Python 3.6 and beyond. The PEP introducing f-strings explicitly states that existing formatting mechanisms will not be removed or deprecated.

Performance Considerations

Contrary to initial assumptions, f-strings demonstrate remarkable performance advantages over str.format(). Benchmarking results indicate that f-strings significantly outperform their counterparts:

f'formatting a string {a}'  # 628 nsec per loop
'formatting a string {a}'.format(a='test')  # 2.03 usec per loop

It's important to note that these results may change as CPython optimizations progress. However, currently, f-strings offer a clear performance edge.

Choosing the Right Formatter

While f-strings excel in readability and simplicity, str.format() may be more suitable in certain situations. Ultimately, the best choice depends on the specific formatting needs and readability preferences of the developer.