[R] How to make R faster?

[ebashi]

Dear R users;
I am using R for a project. I have some PHP forms that
pass parameters to R for calculations, and publish the
result in HTML format by CGIwithR. I'm using a Linux
machine and every things work perfectly. However, it
is  too slow, it takes 5 to 10 seconds to run, and
even  if I start R from the Shell it takes the same
amount of time, which is probably due to installing
packages. My first question is that how can i make R
run faster? and second if I am supposed to reduce the
packages which are being loaded at initiation of R,
how can I limit it to only the packages that i want?
and third how can i make R not to get open each time,
and let it sit on the server so that, when i pass
something to it , i get result faster?

Sincerely,
Sean