It is said that for large programs the startup time of gdb can be improved by indexing symbol files, see for example here: https://sourceware.org/gdb/onlinedocs/gdb/Index-Files.html It would be nice if this there would be a short description how this can be used from within kdevelop.
Could be interesting, some ideas on how to integrate it are welcome.
One way would be by creating indexes for system libraries automatically, and then reusing that info. Doing it for the project binary you are working on is not that good (but may still be required), as it will be invalidated once you change something.