## 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/person.py
props = json.loads(person[3])
        email = props.get("email", None)
        return email or person[0]
    def get_id(self, person):
        return person[0]
    def get_created_at(self, person):
        return person[1]
    def get_team_id(self, person):
        return person[2]
    def get_properties(self, person):
        return json.loads(person[3])
    def get_is_identified(self, person):
        return person[4]
    
    def get_distinct_ids(self, person):
        return person[5] if len(person) > 5 else []
class ClickhousePersonDistinctIdSerializer(serializers.Serializer):
    id = serializers.SerializerMethodField()
    distinct_id = serializers.SerializerMethodField()
    person_id = serializers.SerializerMethodField()
    team_id = serializers.SerializerMethodField()
    def get_id(self, pid):
        return pid[0]
    def get_distinct_id(self, pid):
        return pid[1]
    def get_person_id(self, pid):
        return pid[2]
    def get_team_id(self, pid):
        return pid[3]