PAC - difficult or ?

Guys, I started with fixed income (a random choice). I am half way thru, but Planned Amortization Class is giving me hard. Its very difficult to retain this - atleast in first reading. In particular, I am not comfortable with implications of speed on PAC and support tranche. Am i dumb or its difficult - or perhaps its L2 awakening shock after facing an elementary material. What strategies u adopted to grasp in earlest possible time.

What questions do you have? PAC CMO’s are not all that difficult to understand so maybe you just need a nudge in the right direction.

I never understood anything related to CFA on my first read.