## 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/sql/person.py
from ee.kafka_client.topics import KAFKA_PERSON, KAFKA_PERSON_UNIQUE_ID
from .clickhouse import KAFKA_COLUMNS, STORAGE_POLICY, kafka_engine, table_engine
DROP_PERSON_TABLE_SQL = """
DROP TABLE person
"""
DROP_PERSON_DISTINCT_ID_TABLE_SQL = """
DROP TABLE person_distinct_id
"""
PERSONS_TABLE = "person"
PERSONS_TABLE_BASE_SQL = """
CREATE TABLE {table_name} 
(
    id UUID,
    created_at DateTime64,
    team_id Int64,
    properties VARCHAR,
    is_identified Boolean
    {extra_fields}
) ENGINE = {engine} 
"""
PERSONS_TABLE_SQL = (
    PERSONS_TABLE_BASE_SQL
    + """Order By (team_id, id)
{storage_policy}
"""