Currently, methodcaller is not faster than a plain lambda:

In [1]: class T:
   ...:     a = 1
   ...:     def f(self): pass
   ...:     

In [2]: from operator import *

In [3]: %%timeit t = T(); mc = methodcaller("f")
   ...: mc(t)
   ...: 
   ...: 
83.1 ns ± 0.862 ns per loop (mean ± std. dev. of 7 runs, 10000000 loops each)

In [4]: %%timeit t = T(); mc = lambda x: x.f()
   ...: mc(t)
   ...: 
   ...: 
81.4 ns ± 0.0508 ns per loop (mean ± std. dev. of 7 runs, 10000000 loops each)

(on some machines, I find that it is even slower).

Compare with attrgetter, which *is* faster:

In [5]: %%timeit t = T(); ag = attrgetter("a")
   ...: ag(t)
   ...: 
   ...: 
33.7 ns ± 0.0407 ns per loop (mean ± std. dev. of 7 runs, 10000000 loops each)

In [6]: %%timeit t = T(); ag = lambda x: x.a
   ...: ag(t)
   ...: 
   ...: 
50.1 ns ± 0.057 ns per loop (mean ± std. dev. of 7 runs, 10000000 loops each)

Given that the operator module explicitly advertises itself as being "efficient"/"fast", it seems reasonable to try to optimize methodcaller. Looking at its C implementation, methodcaller currently uses PyObject_GetAttr followed by PyObject_Call; I wonder whether this can be optimized using a LOAD_METHOD-style approach to avoid the construction of the bound method (when applicable)?

Using _PyObject_GetMethod similarly to the way that LOAD_METHOD/CALL_METHOD does seems like a reasonable idea to me -- do you want to make a pull request? It would also be nice to see some microbenchmarks for the change once it's ready.

For what it's worth, in my benchmarks on 3.11, methodcaller was already a bit faster than lambda:

#################### Builtin calls ####################

PS > .\python.bat -m pyperf timeit -s "from operator import methodcaller as mc" -s "reverse_it = mc('reverse')" -s "arr = []" "reverse_it(arr)"
Running Release|x64 interpreter...
.....................
Mean +- std dev: 84.3 ns +- 1.9 ns

PS >.\python.bat -m pyperf timeit -s "reverse_it = lambda x: x.reverse()" -s "arr = []" "reverse_it(arr)"
Running Release|x64 interpreter...
.....................
Mean +- std dev: 95.5 ns +- 2.9 ns

#################### Python calls ####################

PS > .\python.bat -m pyperf timeit -s "from operator import methodcaller as mc" -s "reverse_it = mc('reverse')" -s "class A: reverse = lambda self: None" -s "arr=A()" "reverse_it(arr)"
Running Release|x64 interpreter...
.....................
Mean +- std dev: 140 ns +- 4 ns
PS > .\python.bat -m pyperf timeit -s "reverse_it = lambda x: x.reverse()" -s "class A: reverse = lambda self: None" -s "arr=A()" "reverse_it(arr)"
Running Release|x64 interpreter...
.....................
Mean +- std dev: 159 ns +- 4 ns

If the problem is that methodcaller is not faster than a lambda, then why not use a lambda?

Lambdas are just Python functions and calling them will get faster.

We aren't going to spend time optimizing calls to methodcaller, so you might as well use a lambda.

The PR has been merged, I think we can close this now. Feel free to re-open if still needed.