How to prevent signal from an observer

I have situation where I am facing performance issue when I try to load a set of objects in a sequence . For eg .

1) Load set of objects which subscribe and notify to a signal ABC 2) Load next set of objects which subscribe and notify to a signal ABC

Now the problem is when we notify signal ABC in step 2 , it wakes up the objects in step 1 . This causes performance degrade . Is there a way or a design that I can disable or cancel out signals to particular set of objects ?

NB: We are using observer design pattern here