1- how expensive is drawing a tile
2- how much memory do you have available.
3- what proportion of tiles are static
4- how many layers of tiles do you have?
5- can tiles occlude one-another, do you have transparent tiles?
1- It is fast now but with my game resolution (480*320) if I need to draw 16*16 tiles I will need to draw 600 tiles 30 times every second with 30 fps (and I am not counting with border tiles if I need to scroll and objects, enemies, player, etc).
2- I have a good memory, but I am trying to make an old 2D adventure / rpg style game. I want to aim old computers.
3- Now all my tiles are static. I still need to code animated tiles. (But animated objects like npc and player are done).
4- Hum.. I will have, maybe 3 or 4 layers (depends on map). But just first and second layers can fill the whole screen. Others can't.
5- Yes, that is why I tell that just 1st and 2nd layers can fill all the screen. Others will be for example trees.
And yes, I have. Now I am using .png files with alpha channel. I don't know if I will use this, or just change color in-game (for example pink color in the background).
I have that topic here: http://www.java-gaming.org/topics/load-images-with-alpha/31041/view.html
Thanks for your time, and thanks for all the answers so far.