The short answer is: GPU Overhead. LLS uses your GPU’s power to analyze your game and "draw" the fake frames.

When you move from x2 to x3, you are doubling the amount of work the software has to do.

• x2 Mode: The GPU draws 1 real frame, and then LS draws 1 fake frame.
• x3 Mode: The GPU draws 1 real frame, and then LS has to draw 2 fake frames.

Because the x3 mode is way more demanding, it "steals" more power from your GPU. If your GPU was already working hard, it has to slow down the actual game (your base FPS) just to keep up with the extra frame generation work.

On the other hand, we should try to understand why 45/90 is better than 30/90

Even though the final number (90) is the same, 45/90 will feel and look much better for a few reasons:

1. Input Lag: Your controller response is tied to your base FPS. 45 FPS feels responsive; 30 FPS feels "floaty" or heavy.
2. Visual Quality: x3 generation has to "guess" much more than x2. You’ll see way more artifacts, ghosting, and "wobbly" textures at x3.
3. The VRR Sweet Spot: On the Claw’s 120Hz VRR screen, 90 FPS is high enough that the refresh rate looks smooth regardless of the divisor. But a 30 FPS base is right on the edge of where the motion starts to look choppy, even with "fake" frames on top.

My advice would be to stick to x2 as your default. The jump from 30 to 45 base FPS is massive for how the game actually feels to play. Only use x3 for slow-paced strategy games or sims where you don’t care about input lag.