This function replaces severall patterns in a single iteration. Just pass the text to be replaced and the mappings dictionary to it. Longer words are replaced first.

bulk_string_replace.py

import re

def bulk_replace(text:str, mappings:str) -> str:
    regex = re.compile('|'.join(mappings.keys()))
    return re.sub(regex, lambda x: mappings[x.group()], text)

if __name__ == '__main__':
    mappings = {
        'quick':'slow',
        'fox':'dog',
        'dog':'fox'
        }

    text = 'the quick brown fox jumps over the lazy dog'

    text = bulk_replace(text, mappings)
    print(s)