How to analyse query and added load per modification?
 

AFAIK the only way to analyse the number of queries and server load that a modification adds to your forum, is by comparing the stats you get with the mod working, to the stats you get without the modification. This can be done with the aid of microstats modification.
With this method each affected page of your site needs to be checked; with and without the modification active.

Is there an easier or more effective way?

No I guess.