High humidity slows down a polyester cloth mousepad.

Yes, noticeably. The glide gets heavier and less crisp.

Polyester is hydrophobic compared to cotton, but it’s not magic. In high humidity, the surface still absorbs some moisture from the air. The fibers swell slightly, the surface texture gets a little damp, and friction goes up. The mouse feels like it’s dragging through wet sand, just less dramatic.

This is why many competitive gamers prefer hard pads (plastic, glass, or aluminum) in humid climates. Cloth pads are comfy and cheap, but they’re not consistent when the weather changes.

If you live somewhere humid and hate the inconsistency, a hard pad or a coated cloth pad (like a Glorious Elements) will solve it. But if you just game in a cool, dry room, you probably won’t notice.