Why does querying a PostgreSQL database have an overhead of a few dozens of milliseconds? Everything is in the same place, same local computer.
Whenever my Go application as well as pgAdmin 4 queries the PostgreSQL database, it takes at least a few dozens of milliseconds, however short the actual execution time is. Where does this overhead originate from? What causes the delay? It’s the same without the EXPLAIN ANALYSE.
pgAdmin 4

The problem is with “Total query runtime: 68 msec.” for EXPLAIN ANALYZE SELECT 1; taking 5 microseconds. There’s no way to reduce the client overhead other than querying less?
It's the overhead that the SQL client has, in this case pgAdmin.
Use a different SQL client. pgAdmin isn't known to be the fastest. You will always have an overhead. Parsing and network communication (even if everything is local) can never be avoided. The client needs to receive and display the result - that is where pgAdmin seems to be the slowest option (I have never used it myself, but this question shows up here and on Stack Overflow on a regular basis).