Having missed the earliest entry by Radford last month, due to disconnection in Yosemite, I was stunned to read his three entries of the past month about R performances being significantly modify when changing brackets with curly brackets! I (obviously!) checked on my own machine and found indeed the changes in system.time uncovered by...
Zero Inflated Models and Generalized Linear Mixed Models with R.
Zuur, Saveliev, Ieno (2012).