performance bottlenecks

[sudoUgando]

What are underrated performance bottlenecks in Python applications?

[EimanTahir027]

What are underrated performance bottlenecks in Python applications?

Most people jump straight to “Python is slow,” but the real performance killers are usually less obvious—and often fixable without rewriting everything in C.

Here are underrated bottlenecks that show up again and again in real Python apps:

🧠 1. Excessive object creation

Creating lots of small objects (especially in loops) quietly kills performance.

Why it hurts:

Memory allocation + garbage collection overhead
Cache inefficiency

Example:

slow

result = []
for i in range(1000000):
result.append({"value": i})

👉 Fix:

Use generators where possible
Reuse objects or use tuples instead of dicts when feasible
🔁 2. Hidden O(n²) patterns

Looks harmless, but scales terribly.

Example:

slow

for x in items:
if x in other_list:
...

👉 Fix:

other_set = set(other_list)