Is there a way to save the HHVM bytecode as a file, since HHVM uses JIT bytecode compilation instead of compilation? If not, are there alternatives for modern versions of PHP (5.5.5.6)?
You can create bytecode that is stored in the internal SQLite database, and then turn on Repo.Authoritative mode, whereby HHVM will only use bytecode from SQLite db and will never touch the source .php files. See http://hhvm.com/blog/4061/go-faster