It would be great if actionscript compiler allows to write opcode right in .as files. Like ASM-inline block in c/c++.
Apparat allows to do that but require a lot of work and requirements (scala 2.7/2.9 depends on apparat version) just to compile itself.
Current compiler does not allow to use useful/fast opcodes.
It become critical in some cases (i.e. multiplication 2 ints has a rounding error on some platforms)
Also you can vote for that feature in http://upli.st/l/feature-request-for-flash-and-air and in adobe bugbase https://bugbase.adobe.com/index.cfm?event=bug&id=4103225