The empty weight was bigger by 730 kg, than designed, which decreased performance.

Mental fatigue has also been shown to decrease physical performance.

"Just losing 2% of your body weight in fluid can decrease performance by up to 25%."

This can cause severe instability that is usually solved by extra fins which add weight and decrease performance.

For this reason, QuickStarters can actually decrease performance as a whole.

You don't have to decrease performance either.

It also decreases sexual performance by depressing nerve centers in the hypothalamus.

The overweight football players had decreased performance on tests measuring attention and memory.

Both types had higher drag than expected, which decreased performance.

In my clinical experience, it does decrease performance.