We present an overview of the Monte Carlo event generator KKMCee for lepton and quark pair production in the high energy electron-positron annihilation process. We note that it is still the most sophisticated event generator for such processes. Its entire source code has been rewritten in C++. We have verified that the new version, KKMCee 5.00, reproduces the benchmarks of the older code in FORTRAN 77. We discuss a number of improvements in the MC algorithm.