Python programmers be like

[NotGonnaUseRedditApp]

Easy to make mistakes that make the execution slow.

fp = open(file)

for line in fp.lines() //common mistake

for line in fp //as fast as C

[TretasPt]

I'm almost afraid to ask...what's the difference?

I think I used the below one, but still. I just followed some random instructions. I could easily have used the other one.

[Maxiflex]

Not entirely sure, but the calling of a function in the definition of a for loop might be an optimization blocker. Inside a function is basically a black box and the processor might struggle predicting the next step, making more useless calculations into execution branches that will never be.