Fastest Text search method in a large text file

Question

I am doing a text search in a rather big txt file (100k lines, 7mo) Text is not that big but I need a lot of searches. I want to look for a target string and return the line

Answer 1

First, don't explicitly decode bytes.

from io import open

Second, consider things like this.

with open(path,'r',encoding='UTF-8') as src:
    found= None
    for line in src:
        if len(line) == 0: break #happens at end of file, then stop loop
        if target in line:
            found= line
            break
    return found

This can be simplified slightly to use return None or return line instead of break. It should run a hair faster, but it's slightly harder to make changes when there are multiple returns.