3 passports ago, they were going to raise PP fees (significantly), it was cost effective for me to renew early. I mailed appl. material on a Saturday, I received new PP, 5 days later--regular processing appl.^
[I mailed my material in February...an off season date.]
I try to renew during low season too, and early so that I don't risk problems with countries that require six additional months validity, etc.