The worldkit project compiles instantaneously with mtasc (the predecessor to haxe)--likewise for the as2 branch of modestmaps. The flash compiler shell drops the compile time for as3 modestmaps to under 3 seconds, so I've added this to my .bash_aliases:
alias fcsh="/usr/bin/rlwrap /opt/src/flex2/bin/fcsh"
the rlwrap is to use readline in the flash shell--meaning I can just press up-arrow to get the previous compile command. By default, one has to paste or type the entire command again.
With that, it's close to a reasonable workflow.