Yappi profiler causing horrible slowdown

Question

While doing some optimization tests, I decided to do a comparison of two Python profilers: Yappi and cProfile. I did so with the following python script:

import yappi
import cProfile
import string
import random


def setup():
    strlist = []
    for i in range(1000000):
        strlist.append(''.join(random.choices(string.ascii_lowercase, k=10)))
    return strlist


def execute(strlist):
    new_strlist = []
    for i in strlist:
        new_strlist.append(i.upper())
    return new_strlist

def main():
    execute(setup())

yappi.set_clock_type("cpu")
yappi.start()

main()

yappi.stop()
yappi.get_func_stats().print_all()
yappi.get_thread_stats().print_all()

cProfile.run("main()")

I didn't expect them to be the same, as Yappi was measuring CPU instead of wall time, but Yappi suddenly started causing horrible slowdown. To demonstrate, here's the output of the code above:

Clock type: CPU
Ordered by: totaltime, desc

name                                  ncall  tsub      ttot      tavg      
..p_optimization_baseline.py:20 main  1      0.042419  48.78300  48.78300
..p_optimization_baseline.py:7 setup  1      4.765043  43.22398  43.22398
..on3.8/random.py:386 Random.choices  100..  4.687804  35.68567  0.000036
..python3.8/random.py:399 <listcomp>  100..  16.40414  29.65616  0.000030
..ptimization_baseline.py:14 execute  1      2.818642  5.516596  5.516596

name           id     tid              ttot      scnt        
_MainThread    0      140527431976768  **48.78303**  1         
         17000006 function calls in **4.693 seconds**

   Ordered by: standard name

   ncalls  tottime  percall  cumtime  percall filename:lineno(function)
        1    0.000    0.000    4.693    4.693 <string>:1(<module>)
        1    0.182    0.182    0.342    0.342 loop_optimization_baseline.py:14(execute)
        1    0.036    0.036    4.693    4.693 loop_optimization_baseline.py:20(main)
        1    0.751    0.751    4.315    4.315 loop_optimization_baseline.py:7(setup)
  1000000    0.674    0.000    3.332    0.000 random.py:386(choices)
  1000000    1.968    0.000    2.580    0.000 random.py:399(<listcomp>)
        1    0.000    0.000    4.693    4.693 {built-in method builtins.exec}
  1000000    0.078    0.000    0.078    0.000 {built-in method builtins.len}
  2000000    0.128    0.000    0.128    0.000 {method 'append' of 'list' objects}
        1    0.000    0.000    0.000    0.000 {method 'disable' of '_lsprof.Profiler' objects}
  1000000    0.159    0.000    0.159    0.000 {method 'join' of 'str' objects}
 10000000    0.612    0.000    0.612    0.000 {method 'random' of '_random.Random' objects}
  1000000    0.106    0.000    0.106    0.000 {method 'upper' of 'str' objects}

And yes, it really was taking about 50 seconds IRL. When I set Yappi back to wall time, it started taking about 9 seconds instead. What is happening?

I am using Ubuntu 20.04, Python 3.8, and PyCharm Community Edition 2023.2.2. Yappi was installed through PyCharm's packages manager and is version 1.4.0, which is the latest.