from idlelib.pyparse import Parser
import timeit
code='def f():\n'
print(timeit.timeit("statement",  # for example
                    "p=Parser(4,4)", globals = globals()))

statement     microseconds
Parser            .1  # test timeit code
Parser()         2.2
p.set_code('')   1.4
p.set_code(code) 1.8
'('.translate(map1) 1.5 or 2.2 depending on ParseMap

Translate time is longer for real code and Parser() instance creation time must be well less than 1/10, maybe 1/100 of any answer time.  If we don't reuse instances, though, set_code should be part of __init__ (and tests changed).  Either change is low priority.