Game optimization

[Black Penguin]

Good day.
Thanks for the great game. I was delighted. This is how I imagined it to myself.
Now about the sad.
The first part of the game, before Gordon gets to Xen, the game goes perfectly. I played at high settings. But upon coming to another world, the FPS began to fall. Yes, I was ready for it. On the gnaar's lair, the first time I had to lower the settings to reduce the lags. Continue to play. The second time I had to lower the settings when I arrived at the factory. And then full trash begins. When Gordon goes up in the elevator to the tower. Such lags began that it became impossible to follow the game. I could not do anything, I was dying, not understanding from what. I had to turn on cheats to get through this place. I had to turn on the cheats to get through this place. it was unpleasant, but necessary.
Why does the first part of the game go smoothly, but the second part starts lagging?
I hope you will optimize Xen over time, for a good game.
PS Why is it that when Gordon invades the factory, Nikhilant is so little opposed to him? If he knows there's an outsider here, why is he sending so few troops to intercept? this is not reasonable. I would understand if the first Nihilent not seen in Gordon's threat, but then it becomes obvious this fact. Why are there so many plates to destroy in the Elevator tower? You are surrounded by controllers everywhere, but there are really a lot of plates. Especially in a place where you need to destroy three power plants. There are so many plates that the question arises - why? There are piles of supplies scattered all over Xen, but in reality there is simply no place to spend them.
You guys did well, did what was missing in the original game - made the weapon vacuum cleaner playable, no, not so, the main weapon against opponents. That's cool.