Does using large libraries inherently make slower code?

Question

I have a psychological tic which makes me reluctant to use large libraries (like GLib or Boost) in lower-level languages like C and C++. In my mind, I think:

Answer 1

Even if I only use one or two features of a large library, by linking to that library am I going to incur runtime performance overheads?

In general, no.

If the library in question doesn't have a lot of position-independent code, then there will be a start-up cost while the dynamic linker performs relocations on the library when it's requested. Usually, that's part of the program's start-up. There is no run-time performance effect beyond that.

Linkers are also good at removing "dead code" from statically-linked libraries at build time, so any static libraries you use will have minimal size overhead. Performance doesn't even enter into it.

Frankly, you're worrying about the wrong things.