I had literally never heard of this, so I had to investigate. Turns out, ‘Fast TN’ is a bit of clever branding by BenQ, but it's not without merit. ‘TN’ stands for ‘twisted nematic ...

The company recently launched the BenQ Zowie XL2546X gaming monitor aimed at professional gamers and enthusiasts. The Zowie XL2546X is a premium gaming monitor that uses the company’s fast-TN panel.