How to increase simulation speed
First figure out what is eating away your CPU cycles. Is it
1. Compile time - Use a Make file to compile only files with changes and not all files else just use the incremental compile option in your simulator
2. Loading/ elaborate - If you are using nc-sim / vcs then you are permitted to do incremental elaborate by using -update option when e- lab state. If you use modalism - you cannot gain any time here