Zoning

Okay, I got something down, but I need some help with speed optimization. really need help.

Function ZN_Init(mapn$)
	zn_zone=LoadImage(mapn$)
	zn_size=ImageWidth(zn_zone)
	zn_tex=LoadTexture(mapn$)
End Function

Function ZN_Update(ent=-1)
	DrawImage(zn_zone,0,0)			;The current zone image
	If ent=-1
		ent=zn_ent					;A default parameter
	EndIf
	tx=EntityX(ent)*10;/100			This is the x times map scale.
	tz=EntityZ(ent)*10;/100
	If tx<=zn_size And ty<=zn_size	;If in area
		GetColor tx,tz
		zn_r=ColorRed()
		zn_g=ColorGreen()
		zn_b=ColorBlue()
		;Tolerence Function
		zn_r=(zn_r/128)*128			;Get a solid color. Either 0/128/255. Needs to be fixed
		zn_g=(zn_g/128)*128			;Gives bad output
		zn_b=(zn_b/128)*128
		thisclr$=ZN_GetColor$(zn_r,zn_g,zn_b)	;A Function to return the color name.
		If thisclr$="darkgreen"					; 0 128 0
			zn_inzone=1
		Else If thisclr$="darkred"				; 128 0 0
			zn_inzone=3
		Else If thisclr$="grey"					; 128 128 128
			zn_inzone=2
		Else
			zn_inzone=0							;No zone
		EndIf
	EndIf
	zn_x=tx							;Debug out image position
	zn_y=tz
	Color 255,255,255
	;RuntimeError zn_r+","+zn_g+","+zn_b
End Function

Function ZN_DrawZone(znum=1,ent=-1,size=1)
	SetBuffer ImageBuffer(zn_zone)
	If ent=-1
		ent=zn_ent
	EndIf
	tx=EntityX(ent)*10;/100
	tz=EntityZ(ent)*10;/100
	Select znum
		Case 1					;Get zone number
			Color 255,0,0
			For x=tx-(size/2) To size*2
			  For y=tz-(size/2) To size*2
				Plot x,y		;Draw a box based on zone and size
			  Next
			Next
	End Select
	SetBuffer TextureBuffer(zn_tex)	;Set to terrain texture
	DrawImage zn_zone,0,0			;Copy zone image to texture
	SetBuffer BackBuffer()			;Back to the game
End Function