I was stuck at 147 (or perhaps 145, not sure) for a very long time. After reading TealKnight's comment today, I found 133 path, in a few tries. After that it didn't take me very long to figure out the 131 (which I didn't find so very different, after all). :) After 133 it was more or less ''obvious'' to me, where things can be done differently.
Very good level and good feeling, after you manage to get it to 131.
Somehow, I was on a badly optimized version of the final path, because at no point did I fundamentally change my path! All I did was optimize straight to 131! But now I'm kind of curious to know what the optimal 133 looks like... Can it be forced?