Comment by chunkyguy

> This introduces performance issues larger than the typical ones associated with vtable lookups.

Don't know about other programming languages but with Objective-C due to IMP caching the performance is close to C++ vtable

  Name Iterations Total time (sec) Time per (ns)
  C++ virtual method call 1000000000 1.5 1.5
  IMP-cached message send 1000000000 1.6 1.6

https://mikeash.com/pyblog/friday-qa-2016-04-15-performance-...