ZeroTierOne/ext/libpqxx-7.7.3/include/pqxx/doc/performance.md

Performance features

If your program's database interaction is not as efficient as it needs to be, the first place to look is usually the SQL you're executing. But libpqxx has a few specialized features to help you squeeze more performance out of how you issue commands and retrieve data:

• @ref streams. Use these as a faster way to transfer data between your code and the database.
• std::string_view and pqxx::zview. In places where traditional C++ worked with std::string, see whether std::string_view or pqxx::zview will do. Of course that means that you'll have to look at the data's lifetime more carefully, but it'll save the computer a lot of copying.
• @ref prepared. These can be executed many times without the server parsing and planning them anew each time. They also save you having to escape string parameters.
• pqxx::pipeline lets you send queries to the database in batches, and continue other processing while they are executing.
• pqxx::connecting lets you start setting up a database connection, but without blocking the thread.

As always of course, don't risk the quality of your code for optimizations that you don't need!