My yabause simulator simulates that this game is not normal and is not convenient for debugging. You can say a few more games that will be decompressed in the game. We can test whether the optical drive reads 200kb of data and the optical drive reads 100kb of compressed data. Unzip with cpu and see which one is faster
btw, SotN not only read the data but also decompress the map file several times
Again, I don't think any decompression is really the issue here. Not enough to explain a ~9 second load time. If the decompression was truly whats taking so long, then we should see improved load times in emulators that run too fast like Mednafen. In these emulators the game exhibits no slowdown as the emulators run faster than the real hardware. So if it's truly a CPU issue accounting for these long load times, we should see an improvement here. But we see no improvement in these emulators when it comes to loading.
The one thing these emulators do emulate somewhat properly when it comes to speed is the disc drive speed, because if they didn't you'd have some terrible issues with games that stream data off the disc and expect it to come at a certain rate.
Although I have not debugged the ps version, I have played the ps version many times before. After the ps version passes through the area, not all the files of the entire stage level are read into the memory. It seems that it should be read in stages. You are interested. You can debug the ps version and see if it is all loaded into the entire stage level file at once
The file sizes for the areas aren't that big in either version. Were looking at maybe 400-600KB max from what I'm seeing. Both systems have 2MB of RAM and 2x Speed disc drives that can read ~300KB/s. So loading that data in should only take 2-3 seconds once the laser gets to that part of the disc. Which is about what we see on PS1 when you reach the end of the hallway. It actually looks like the PS1 isn't doing any preloading watching the Memory viewer in Mednafen. Data doesn't start to load in until you reach the end of the hallway and try to exit out the door, where the game will pause for 2-3 seconds.
And looking at memory dumps of the PS1 version, all the files for that area are loaded in. For example if I open up the up a Main RAM dump from when I enter the Alchemy Lab in a hex editor and also open up NZ0.BIN (Alchemy Lab) I can see the entire file is loaded in at offset 0x180000. F_NZ0.bin is loaded into VRAM, not in one big continuous go, but it's broken up and loaded into different spots, which makes sense since that's the tile data.
btw: The ss version of the file is sorted by sort
Yes they're sorted alphabetically, but they're all in a root directory, and other files it needs are in other directories. So the game has to traverse large directories and go looking for things in different parts of the disc. When it comes to load times the thing that causes it to take longer isn't just reading the data, it's the time it takes for the drive to seek to the right part of the disc.