The generated PDF has 9375863 bytes, when generated using:
pdfTeX 3.14159265-2.6-1.40.21 (TeX Live 2020)
kpathsea version 6.3.2
Commits to master should not change the byte count of the generated PDF:
yarn pdf
ls -l latex_pdf/sicpjs.pdf
and verify that the file has 9375863 bytes.
Update (23/1/2022): After upgrading to LaTeX 1.40.23 on MacOS Monterey, the byte count changed as follows:
pdfTeX 3.141592653-2.6-1.40.23 (TeX Live 2022/dev)
kpathsea version 6.3.4/dev
yarn pdf
ls -l latex_pdf/sicpjs.pdf
gives 9488830 bytes, and many changes in hyphenation and pagination, compared to what you get with 1.40.21.
Update (11/2/2022): The fix of #747 added two bytes, so the built version at https://sicp.sourceacademy.org/sicpjs.pdf now has 9375865 bytes.