Basically, when you create a handle (a handle is anything but a integer, real, string, code, boolean, such as a unit, or a destructable, or a multiboard) it stores the handle is memory.
If you dont set that handle to something (a local or global) then destroy it later, that handle will be undestroyable, so your game is always going to be processing that handle, thats more delay/lag to think about.
Example of a leak:
JASS:
function ThisLeaks takes nothing returns nothing
local unit u = CreateUnit(...)
call DoStuffWithUnit(...)
endfunction JASS:
function ThisDosentLeak takes nothing returns nothing
local unit u = CreateUnit(...)
call DoStuffWithUnit(...)
call RemoveUnit(u)
set u = null
endfunction
You must destroy the handle when you'v finished using it!
Thats what a leak is, when you have lost the reference to a handle, so its undestroyable.
