They could mean to compile to make faster, but to still be used from within mIRC only. If I understand it correctly, the mIRC "language" is still interpretted everytime it does something, much like in the older days, you had "basic" which just about anyone could right, and then you had assembly language - both running on the same machine (in this case, in mIRC), but one is faster.. Then obviously, some compilers could take "BASIC" and convert it into assembly which got encoded as well. Not quite as quick as properly programmed assembly, but was faster than "BASIC"...
At least, that's the impression that I got - but I could be wrong.. To actually implement the feature would probably require a third party to make something that would do an idea I mentioned a few threads back - convert a mIRC script into a DLL.. Somehow, I doubt that'll happen or would be easy to do.
Oh well.
