Code `{% reviews|length %}` will cause a query to fetch all reviews from database and then apply `len()` python function. In this template only two values are needed: count of all reviews and first 3 reviews. So, we don't need all reviews, just 3.

Currently, this template (and corresponding view) will create one reviews query: 

1. `reviews.all()`

After these modifications, two queries will be executed:

1. `reviews.count()`
2. `reviews.all()[:3]` (with `LIMIT 3`).

To my mind, the second case is better. For example, if there are 100 reviews, in second case only count and first 3 reviews will be retrieved, whereas in first case all 100 reviews will be loaded to memory.