Ever since the new Minecraft loading screen was added, it not only takes longer to start the game but also right before the Mojang logo and loading bar appear, my whole pc starts having less frames and huge lags.

Some of my friends can confirm this.

This is a huge problem as I always think my pc will crash any moment. What causes this? What has been changed in the new loading screen?

This also is not a performance issue because after the game is loaded, it works perfect with no frame drops or anything. (I have a semi powerful machine)

Demonstration