This boss is kicking my ass and I fail to see any, like ANY, pattern here (nor any semblance of fair play).

1. Naga has only 3 attacks: earthquake, laser barrage and spear toss. and only laser is used even remotely coherently (when I'm exposed).
2. Oftentimes the fight starts with the earthquake attack immediately upon boss spawn, I've no way to react to it nor evade it. The range of the attack is also pretty erratic.
3. I am eager to believe that the spear explosion should hit through walls and lasers home in on me, cause ancient games play it cheap, but idk how to fight a boss that only spams earthquake and nothing else. I cannot possibly make it stop, it uses it regardless or distance and my actions. can't jump over the shockve either.

I have a hard time believing that any of this this is normal, especially that I don't recall having such issues back in 1999.

I know that difficulty ramps up dramatically between Homicide and Suicide difficulty levels, do you remember what you played it at in 1999? It may be there is some wonky clock speed math going on that wasn't an issue at 400 MHz, but is a crapfest at 4 GHz.

Intel Celeron 300 MHz, Voodoo 2 16 MB, and something like 32 MB RAM. I suppose cutting the game off extra cores won't help me much ;)

I have seen this fight on youtube and it's totally not how it goes for me. I made sure to enable Vsync but I don't think the boss scripting relies on it as it didn't help. Are there any parameters I could use (the launcher allows me to add parameters)?

This boss is where my suicide difficulty playthrough died. There was just no way I could beat Naga when all I had was 3 seconds before the earthquake attack would simply instakill me.

After a lot of tries I managed to beat this glitching boss, by running around like crazy and spraying it with double ingrams. It took my whole pistol ammo and I got hit by an earthquke once so idk if I could pull it off on "hard" (I'm on Homicide).

It is doable even on the suicide difficulty, provided you have enough flares.

Spawn the boss but don't drop down. Now make a quicksave. Wait for the boss to use the laser attack, just as it ends, rush in. Make sure to always actually run (hold shift). First stop is the life seed opposite of where you drop. Then turn around and climb the rubble to the top ledge above the life seed. There is ammo and most importantly, an Anger powerup (massively increased damage). Then drop down and rush for the big armor on the other side below. Finally, go out into the middle, face the boss directly and start pumping flares into him. The reason for flares is that it pretty much locks the boss into spamming only the ground slam move. Simultaneously, keep moving forward and backwards, changing direction at the exact moment the boss slams the ground. That way, you can avoid most of the ceiling rubble. You should be able to melt most of the boss' health this way. Then finish him off with anything else.

This entire procedure is likely to take a lot of tries as the ceiling rubble also has a degree of randomness to it. But I reached the boss with 20 health and was able to beat him this way.