configuring R-2.6.0 for speed

Hi

I have checked out R-devel from subversion and configured it with the  
following command

./configure --with-blas='-framework vecLib' CFLAGS="-g -O2 - 
march=nocona" CXXFLAGS="-g -O2 -march=nocona" FFLAGS="-g -O2 - 
march=nocona" FCFLAGS="-g -O2 -march=nocona"

followed by make && make install. This works in the sense that R  
starts up fine. However, my session seems to be very slow compared to  
R-2.5.1 (which I had installed from the binaries at CRAN). Slow means  
for example that loading a large RData file takes much longer. Is  
there any configure flag I am missing? What are the exact configure  
command used to build the CRAN binary?

(I am using the latest version of OS X on an Intel MacBook with the  
newest Xcode and the gfortran from CRAN).

Jim