(See the best response by Yut Put.)

Problem description:

We've always wanted to implement a nice minimap as such in our games for some time but we could never figure out how to even go about it or get started. There are some minimap libraries on BYOND's Resource section but I am looking for something that would take a less major toll on performance for players.

Any Ideas or Concepts are welcome. Please and Thank you

Im fairly sure he made physical copies of each map and just moved the players map image on the map in the bottom right corner based off where they are
Probably gunna have to do some math and find an equation to match ur location with where it would be on the minimap
Can't think of anything more efficient than that
Best response
the fastest way to do this is to probably have a baked version of the map and separate them into 100x100 chunks or however you want to separate it(you can screenshot this from the dream maker map editor) and then display the background image for the chunk you're in. Each chunk could have a global screen object that updates when a player moves and is in the player's screen so that it never scales up as more players play. The update proc could have a cooldown limit so that it only updates once every half second and the update procedure would just be overlays = list()+player_images. When a player enters a new chunk the player_image is removed from the previous map's list of players and added to the new one. When the player moves the player sets its image's pixel x and y. In this way, there are no calculations needed to determine who is in view or what that player's pixel x and y on your minimap are and it overall keeps the time complexity of displaying the players very low
Hmm @YutPut I'm not sure i completely understood what you mean. My maps as of right now are 300x300 though.

How would I then get the image to follow the player's movement if not by calculating the position and all that?
In response to Zagros5000
I figured thats what it was too but wanted to get some other's opinions. I guess figuring out such an equation would be the hardest part for me.
Well ur map is 9600x9600 pixels if the mini map is 150x150 pixels every 64 pixels u move would be 1 on the mini map
Just grab the players pixel x/y location in that z lvl and divide by 64 and thatlle be the point on minimap u Shud put the player icon

If u wanna use a different size just do 9600/size of mini map
But this would just get u 1 giant mini map for each zone