Parallel computation on vectorized function

Dear all, I am looking for some way on how to parallelize some computation on a vectorized function. I have a custom made vectorized function and also have a very length vector (of length some 2 million entries.)

There are equivalents for all apply family of functions however could not find any way how to apply some parallel computation on a single vectorized function. I have tried with making my vector to list (of same length) and then applying sfLapply() function. However this process is actually taking more time.

I am using windows vista machine and snowfall package.

Any help will be highly appreciated.

Thanks,