Comment by schobi

The reason is not bad SW engineering for the simulator, but rather a different goal.

Cycle accurate simulations means you emulated the exact CPU behaviour - easily spending 1000 instructions to compute what happened and maybe even log the results for later inspection. You want to be flexible to try different things, so not over optimize and still compare detailed behaviour.

If you build a performance multi core CPU and emulated on a single regular core, I would not be surprised to be 1000000x the runtime.