Boost Python Speed: 4 Simple Tricks to Cut Execution Time by Up to 20%

Today I want to share four time‑saving Python tricks that can reduce execution time by about 10‑20%.

Reversing a list

Python offers two ways to reverse a list: slicing or the reverse() method. The built‑in reverse() modifies the original list, while slicing creates a new list.

Performance test shows reverse() is faster (≈10.7 µs per loop) than slicing (≈15.6 µs per loop).

Swapping two values

You can swap two variables in a single line without a temporary variable: variable_1, variable_2 = variable_2, variable_1 The same technique works for dictionary entries, reducing iteration and data‑conversion overhead.

Looping inside a function

Placing a for loop inside a function means the function is called only once, which can be slightly faster than calling the function repeatedly in an outer loop.

Reducing function calls

When checking an object’s type, isinstance() is the most efficient, followed by id() and type(). Avoid placing repeated operations in loop conditions; compute them once before the loop.

# Check if num is an int type
type(num) == type(0)   # three function calls
type(num) is type(0)    # two function calls
isinstance(num, int)    # one function call

Import specific objects directly (e.g., from X import Y) instead of importing the whole module, which saves a lookup.

In summary, extensive use of Python’s built‑in functions can speed up programs while keeping code concise and readable.

For more details, see the Python built‑in functions reference.