How would you speed up a slow report?

Start by identifying what is actually slow — load the report and watch which components resolve last. It is usually one or two, often a blend or a community connector.

Then, in rough order of impact: use Extract data to create an aggregated snapshot; aggregate upstream so Looker Studio queries summary rows rather than raw ones; split dense pages, since every component is its own query; replace blends with an upstream join; and lengthen data freshness so results cache longer.

The underlying principle is that a report over a million raw rows will never be fast however it is built. The work belongs before Looker Studio sees the data.