Map Editor (efficiency)

I’ve made other map editors before, but they haven’t been too efficient. I’m trying to do things right now… Previously I was making each tile a movieclip then just manipulating the movie clips. But when there are maps of say 50X50 that’s loading 2500 movieclips, which can often slow things down a lot. What would be another method?

Using Bitmaps? I’m not exactly sure as I haven’t worked with AS3 for a while, but I’m pretty sure I recall that bitmaps don’t support the right events, am I right?