speed up in R apply

Hi,

I am doing some simulations and found a bottle neck in my R script.  
I made
an example:

a = matrix(rnorm(5000000),1000000,5)
tt  = Sys.time(); sum(a[,1]*a[,2]*a[,3]*a[,4]*a[,5]); Sys.time() - tt

[1] -1291.026
Time difference of 0.2354031 secs

tt  = Sys.time(); sum(apply(a,1,prod)); Sys.time() - tt

[1] -1291.026
Time difference of 20.23150 secs

Is there a faster way of calculating sum of products (of columns, or  
of
rows)?

And is this an expected behavior?

Thanks for your advice in advance,