@rhettinger
Measured a performance improvement of 20% ✅

Test env

• OS: Windows 11
• Processor: Intel Core i7-11800H
• Python: 3.13.3 - CPython

Test case

def aRandomComplex():
    return complex((random.random()*10000 - 5000), (random.random()*10000 - 5000))


random.seed(0)
v1 = [aRandomComplex() for _ in range(2000000)]
v2 = [aRandomComplex() for _ in range(2000000)]


def testCase():
    _complex_sumprod(v1, v2)

Perf Measurements

Performed over 50 executions:

Before

min:     0.7268
max:     0.7901
mean:    0.7415
median:  0.7392

After

min:     0.5864
max:     0.6410
mean:    0.5932
median:  0.5918

Performance improvement: 20%

@rhettinger
While checking the performance improvement, I checked if the results differ between the current and new implementation.
Got a perfect match on my large test case✅