Just finished looking over your map, there's too much to say to fit into a comment, so i'm doing it like this instead. Brace yourself! :P

My computer (a low-medium power macbook) absolutely cannot handle this map. Which is a shame, because it looks topographically awesome. There are some odd choices with chokepoints and base placement, but nothing seemingly broken, and it looks like somethin really potentially interesting, if not for the 15 fps that me and many others are going to get.

--So first, performance

"optimizing" this map is gonna be kinda easy-hard. The map editor doesnt handle high-object-count maps very well, the rough acceptable limit is 2000 objects (hilly maps that obscure objects seem to tolerate less, while flat ones tolerate more, odd...). To get this map running by ravenfield standards, you're prolly gonna have to make alot of streamlining changes. I'd suggest a couple:

-Ditch the planar rocks: looks like there are potentially hundreds lining the roads and in the mountains. Just sculpting the mountain and ridges out of terrain is not only easier to manage, but gives you more flexibility with shape, color, ect. Rid yourself o' those, and you're already on your way.

-Trees...: I usually barely use trees; bots shoot through em, and they lag when too many overlap visually. Here, trees are a central part of the aethetic, so don't ditch em, but maybe reduce them, and place them more strategically. (you could have done a lot worse, though)

-Dirt barriers: noticed that you use em for roadside barriers. Cool use for them, which is why it sucks to say that they may be a problem too... maybe experiment with replacing them with more terrain sculpting, but otherwise, idk...

--Next, design

I've actually done something similar, where i get super enthused with populating an area, only to notice afterwards that all that cool detail is kinda misplaced... Noticed several instances where you had crates and stuff piled up in a lot, serving no real purpose other than aesthetics since they were well out of the way of the main attack routes. All those boxes could be reduced and "merged" into larger ones, and would serve more of a purpose moved closer to the flags and attack routes.

Similarly, many of those neat roadside barricades and sandbags suffer from being kinda ignored by the dumb bots. Plus, the map is so huge and spread out, you can kinda afford to let some of those roads be without them.

There are also a lot of identical archi houses, and many of them will never be used in battle for anything other than obstacles (as opposed to archipelago, where the 20-something houses that are there all offer a potentially valuable approach/defense strategy). I don't think the houses are a lag problem, but you could try varying them a bit with different buildings, hills, parks, ect.

...
Aaaand, im not sure what else to say. The winding road approach is one that hasn't really been tried much at all, besides mountain range (which is considered a bad map for doing so, but yours seems to counter some of the problems that come out of a linear setup). I really would like to see it evolve, there aren't too many others like it.... no less because it's a map called "island" and "war" that isnt awful, but heyy...

Swing by the Ravenfield Discord if you need help, im there some of the time. Also, if you do dome by, and if you feel safe doing so, could you send me the raw map file to look at? I'd like to see how many things you placed, and how many can be quickly deleted.

Anyways, good luck with this!
-Starstrafe