Sentry now showing performance in dashboard

Hello,
In Sentry dashboard, the “performance tab” is empty, even when i follow the setup instructions.

Am i doing something wrong? I am using sentry-sdk==0.17.8.

import sentry_sdk
import requests

sentry_sdk.init(
    dsn="my_DSN",
    traces_sample_rate=1.0
)

with sentry_sdk.configure_scope() as scope:
    scope.set_user({'username': 'test'})
    scope.set_level('info')

for x in range(5):
    response = requests.get('http://sentry.io')
    print(len(response.content))