May i give another hint: if you are only making a version to test lighting or other effects and arent making it a final version use the fast option for compiles. this skips the portalflow step. However, never release a final map with a fast compile as then your map will be alot more laggy.
Still, using hints and func_details can be usefull. You can check if the leafs are simplified by loading the portalfile in hammer. the more blue lines you see, the more leafs you have. and each leaf increases the compile time. However, dont be overkill in trying to get rid of them, leafs are also used in reducing the ammount you can see which improves performance.