R install packages without loading in .Rprofile

Question

I want to make sure I always have my most commonly used R packages installed without my intervention. This is useful as I work across multiple computers, often reformat my computers, and sometimes have new packages that I want to add to this "commonly used" list and don't want to have to manually install it on every machine. Basically, I just want R to install missing packages for me whenever it starts up.

Currently I'm using a .Rprofile that installs my package list whenever I start R. It contains the following:

packages <- c("list", "of", "packages")

for (p in packages) {
  if(!suppressWarnings(require(p, character.only = TRUE))){
    utils::install.packages(p, repos='http://cran.us.r-project.org')
  }
}

There are a couple of issues:

1. Running install.packages when the package is already installed seems to download the package (or meta data?) from the repo, and maybe attempts a reinstall
2. I'm using require to check whether a package is already installed, but that has the side effect of also loading the package. I don't want any package loading to happen, only install (if needed)

How do I set this up so that 1) a package will be installed if it isn't already, and 2) not load the package at startup? I think ultimately what I'm looking for is a way to check whether a package is installed without having to load it

I've considered two ways around this, but neither are ideal and would like to avoid them as solutions:

• Use a package manager like Packrat. I'm not a fan of essentially creating managed virtual environments for all of my projects. It would take up unnecessary space to have multiple copies of the same package files on my machines
• A common solution to this problem (e.g. Elegant way to check for missing packages and install them?) is to check whether a package is found in installed.packages(). But this ends up being really slow (which is especially a problem at startup) if you have a lot of installed packages

I've seen many questions about this, but all of the solutions I've seen either load packages using require or checks against installed.packages(). Is there another way?