Yes, looks like it. The default symbol lookup can be really slow in some situations, especially in large C++ projects with can contain many symbols that share a long common prefix thanks to C++ name mangling.
"Optimising the linked output" seems a bit vague but that's about as clear as the man page.
If level is a numeric values greater than zero ld optimizes the output. This might take significantly longer and therefore probably should only be enabled for the final binary. At the moment this option only affects ELF shared library generation.
