While browsing PPS Mega tasks, I saw that some took 4100 s, some 5400 s. I assumed the latter had the larger FFT size and larger k, but not so.

The 4100 s tasks had FFT = 256k, the 5400 s ones had FFT = 240k.

Here are examples of each: 4100 s and 5400 s or the whole list here.

The difference seems to be the pass1 and pass2, in one case pass1 is larger, in the other pass2 is larger. And a is either 3 or 5.

What do these parameters mean and how do they influence the CPU time in such a way that smaller FFT size means longer CPU time? Especially since the tasks with shorter run times had the larger k and accordingly larger FFT.
____________
1281979 * 2^485014 + 1 is prime ... no further hits up to: n = 5,700,000

Ok, thanks I will continue in that thread.
____________
1281979 * 2^485014 + 1 is prime ... no further hits up to: n = 5,700,000