The footprint is very minimalistic. I have 15+ years of Postgres DBA experience, and what this tool does basically is what I usually do myself with performing Postgres health checks under heavy load. But in automated fashion :)
We very carefully choose approaches and queries that we run on production servers. And it is used under heavy loads (dozens of thousands of TPS) daily.
There are certain places that can be heavy. For example, if you have 1 million indexes (yes, it happens, sometimes), the SELECT query for bloat analysis will be slow. Actually, with default settings, the tool limits itself setting `statement_timeout = '30s'` (can be adjusted using CLI option `--statement-timeout`). So, in databases with a huge number of objects, you should expect that F004 and F005 reports will be missing.