Speed optimizations

[miron]

Check for string concatenation

Replace with list.append() and then ‘’.join(list) (O(N) instead of O(N^2))
Alternatively:
list comprehension, generator expression, map, itertools, array.array(‘u’), bytearray, io.TextIO, io.BytesIO or writelines() the list to file, or directly write() strings to file.
Also f’’ 2x faster format() 2x faster str + str

Check for global variables

Replace with local ones, which are faster, also hoist attribute lookups outside of loops (if method doesn’t change object), by assigning to variable for speed improvement (modest speed improvement also for builtins when assigned to local namespace).

Replace loops

Use list comprehensions, generator expressions, map and filter (only with builtins, not lambda) instead.