Django 3 performance regression.

[Nicolas]

After upgrading from the latest django 2 version, i experience real slowness.
Django 3 is really really slow!
I use pm2 to start my app and my database is a PosgresSQL 12 running on a ubuntu 20.04 with Python 3.8
I don't understand why this is so slow... Maybe you can help me understand this

[Mariusz Felisiak]

Thanks for this ticket, however there is no way to move it forward. We can reconsider this ticket if you can provide more details, point specific places where you've noticed a performance regression, and prove that it's caused by Django itself (not 3rd party package or others).

[Nicolas]

You just close this like that, are you kidding no investigation at all!
I can tell you the problem is django 3 as i test this by only updating it.
On any filter query with relation and django rest framework serializing foreign key this is 10 times slower than under django 2.
A little investigation on your side is requested. Don't put this under the carpet.

Here are my requirements:

asgiref==3.2.10
cairocffi==1.1.0
CairoSVG==2.4.2
certifi==2019.9.11
cffi==1.13.2
chardet==3.0.4
cssselect2==0.2.2
defusedxml==0.6.0
Django==2.2.7
django-cleanup==4.0.0
django-cors-headers==3.2.0
django-countries==5.5
django-crontab==0.7.1
django-extensions==2.2.5
django-filter==2.2.0
django-maintenance-mode==0.13.3
django-model-utils==3.2.0
django-optimistic-lock==1.0.0
django-stubs==1.2.0
django-unused-media==0.1.13
djangorestframework==3.10.3
djangorestframework-stubs==1.0.0
djangorestframework-xml==1.4.0
fpdf==1.7.2
html5lib==1.0.1
icalendar==4.0.3
idna==2.8
mongoengine==0.18.2
mypy==0.720
mypy-extensions==0.4.3
pdfrw==0.4
Pillow==6.2.1
pipdeptree==0.13.2
psycopg2-binary==2.8.4
py3dns==3.2.1
pycparser==2.19
pymongo==3.9.0
Pyphen==0.9.5
python-dateutil==2.8.1
python-magic==0.4.15
pytz==2019.3
pyuca==1.2
requests==2.22.0
sentry-sdk==0.13.3
six==1.13.0
sqlparse==0.3.0
swapper==1.1.1
tinycss2==1.0.2
tqdm==4.39.0
typed-ast==1.4.0
typing==3.7.4.1
typing-extensions==3.7.4.1
urllib3==1.25.7
WeasyPrint==50
webencodings==0.5.1

Sincerely

[Claude Paroz]

Nicolas, you have no chance getting more attention by being rude.

Thousands of projects already migrated to Django 3 without noticing a performance regression like you describe.

So this must be something related to your project and/or dependencies. How could we be able to guess the issue without any hint? We are not magicians.

Please reopen only if you can give us a mean to reproduce the problem (sample project, code snippet, etc.).