## Bug description

Currently, decide endpoint takes 10+ seconds on kea.js.org.

This means that for first-time visitors autocapture nor session recording will be turned on for that long - losing valuable information.

When measuring this yesterday via shell ([slack thread](https://posthog.slack.com/archives/C0113360FFV/p1604951621008400)), the culprit was feature flags cohort checking. In this case, the cohort user was checked against was defined against the following action:

![Screenshot from 2020-11-10 11-41-32](https://user-images.githubusercontent.com/148820/98657215-49582e80-234a-11eb-9669-37d55e0d23bd.png)

Which currently looks through events of the data for that team.

## Expected behavior

Decide endpoint should use cached/materialized cohort ownership rather than calculating it on the fly.

## How to reproduce

1. Create an action with some selector
2. Create a cohort for has done action at any point
3. Create a feature flag using the cohort.
4. Measure /decide endpoint latency

## Environment

Cloud 

## Additional context

cc @EDsCODE who made it not time out by https://github.com/PostHog/posthog/pull/2299

#### *Thank you* for your bug report – we love squashing them!
ee/clickhouse/models/test/test_cohort.py
from datetime import datetime
from uuid import uuid4
from ee.clickhouse.client import sync_execute
from ee.clickhouse.models.cohort import format_filter_query, format_person_query
from ee.clickhouse.models.event import create_event
from ee.clickhouse.models.person import create_person, create_person_distinct_id
from ee.clickhouse.models.property import parse_prop_clauses
from ee.clickhouse.util import ClickhouseTestMixin
from posthog.api.test.base import BaseTest
from posthog.models.action import Action
from posthog.models.action_step import ActionStep
from posthog.models.cohort import Cohort
from posthog.models.event import Event
from posthog.models.feature_flag import FeatureFlag
from posthog.models.filter import Filter
from posthog.models.person import Person
from posthog.models.team import Team
from posthog.models.utils import UUIDT
def _create_event(**kwargs) -> Event: