Line-of-Sight Performance issue, How use efficiently?

Hello,

I'm working on tile based line-of-sight, in my case there is Unknown tiles, Out-of-sight tiles (OOS tiles) and shadow tiles.

They work in way that is hard to explain, so here is example:

Now it works and looks good, but issue is performance.

The way I implemented line of sight related to walls, seems to really choke performance.

For example, OOS tiles, I hide them if you have line of sight to it. Of course, issue is that if wall (sight blocker) and that OOS tile are in same tile then player will never have sight to that.

So I made

player has LOS on wall

Wall is overlapping a OOS tile

Then > hide OOS tile

Map size (more OOS tiles) doesn't really impact performance but as I add more walls performance start to fall. I assume there's something with that "Wall is overlapping a OOS tile" that causes issues...

Any suggestions how I make that detection properly?

I tried this:

Player has LOS on wall

then For each wall

Wall is overlapping OOS tile

Hide OOS tile

This really improved performance, tho, debug says that vision controls still uses a bit of cpu.. but atleast its not chokingly bad.