Got it ! Thanks Paul !
Just few hours ago NXP tech support was convincingly telling me that K66 has NO additional cache besides the tiny FMC one. That is what happens when design travels the path of multiple company M/A.
I was evaluating the relative benefits of 3.5 vs 3.6 for my design that does not require high clock speeds (48MHz works just fine), but I want the convenience and efficiency of the FPU for DSP functions and I am at 100% pin usage on 3.2 and may need few more. I got 3.6 from you, but it looks like 3.5 is just what I need going forward. Basically the figure of merit for me is Jouls of energy per single 256point complex FP FFT or a complex FP FIR and such.