Nebular lags when I use custom theme

Question

So it's my first time using nebular, and I tried to customize it a bit, but whenever I customize it the whole page starts lagging hard, and the reason for that, I think is that it loads whole nebular styles like 3200 of them, like it is shown in image , but whenever I use default configuration these styles aren't loaded and the page runs fine. So am I doing something wrong or u cant customize nebular without sacrificing page performance? This is my configuration of the custom theme :