From the good ol’ BBC:

Connections between the left and right hand sides or hemispheres of the brain are faster in left-handed people, a study in Neuropsychology shows.

The fast transfer of information in the brain makes left-handers more efficient when dealing with multiple stimuli.

Dr Cherbuin explained that people tended to use both hemispheres for tasks which are very fast or very hard and which require interpretation of a lot of information, such as computer games or driving in heavy traffic or playing sport.

Chartered psychologist, Dr Steve Williams said left-handed people tended to be better at using both sides of the brain.

“It’s certainly very interesting. It’s always been said that left-handers are different from right-handers in that the are less consistent with their left-handedness.

“This seems to go with evidence that left-handers use both sides of the brain for language – that they are more bicerebral. They get faster at it because they’re having to use both sides of the brain more.”

“In football, being able to shoot with either foot is a huge asset (each foot like each hand is under opposite-side control) and I’ve heard that left-handers tend to have better backhands in tennis,” he added.