For most dynamic languages, the available speedups aren't in simple compilation, but in removing the runtime type checks, method lookups, and other slow operations. This needs the ability to guess at what the code is going to do based on past behavior, and generate specialized versions that get thrown away if the guesses are invalidated.

So, for example, you might see that the last 100 calls to a function were done with integers, so you can generate a variant of the function that only works for integers, and check if it's applicable when you enter the function. If that function stops getting used, you can throw it away.

Doing that well ahead of time requires an extremely good idea of how the program will behave at run time, and even with good information, is still very likely to bloat up your binary hugely. (Facebook used to compile their PHP codebase to a multi-gigabyte binary before moving to HHVM, for example).