Both parts run R in your browser. Part 1 downloads about 20 MB: R, and the two repositories' lists of packages.
Part 2 downloads about 18 MB more for Biostrings and the packages it needs, and loading Biostrings takes several seconds.
1. Does a package have a webR build, and so does everything it needs?
2. Bioconductor's Biostrings, on the HBB coding sequence