right I wanted to ask would radiant handle like open world size map like need know how big u can build well me lol
I had idea as just got my new gaming pc is change waw zombie feel to open world may take a lot time take out round base etc. make it so u can go anyway change everything almost as I spent almost year and half on one map and then my laptop broke so now im starting all over I want open world game but using world at war game engines im bad at spelling as well that my weak spot

would radiant handle like open world size map

No.

Edit: to be more specific, World at War's engine wouldn't be handle a map file produced by Radiant with that much content in it.

Don't quote me on this but isn't there something called 'portalling'? I believe it is used to keep certain parts of the map 'unloaded' when they are not visible to prevent unnecessary lag? Not sure how this works or how to do it but it may allow you to make larger maps with less lag that the game can actually run. Not many people use portalling because most computers can run a standard sized map without it at good frame-rate, and it would be a waste of time/resources for most maps.

Don't quote me on this but isn't there something called 'portalling'? I believe it is used to keep certain parts of the map 'unloaded' when they are not visible to prevent unnecessary lag? Not sure how this works or how to do it but it may allow you to make larger maps with less lag that the game can actually run. Not many people use portalling because most computers can run a standard sized map without it at good frame-rate, and it would be a waste of time/resources for most maps.

that has nothing to do with if a map can be big or small, neither lag caused by high poly count.
waw has stuff like ent limit, path nodes limit,etc,etc,.. so if you're making an open world map, this last limit would stop you as theres no use in having a big map if zombies cant go to all the map. search in google for radiant engine limits

portaling only controls what is "rendered" not what is "loaded"

So basically itll stop the engine wasting itself on drawing things that are out of site and therefore unnecessary

Its basically optimizing, the biggest advantage of this is to stop models from "popping" in and out of view and to stop FPS drops