Does sex affect your sport performance?

Probably not. Sexual tensions if relieved prior to sproting activities could be beneficial. If one has prolonged sex and tires themself, this could reduce sports performance. Unless your are a competetive athlete at a high performance level, consider the pros and cons and make your best judgement. I would doubt any serious deleterious effect.
No proof of affect. To my knowledge there is no clear proof that sexual activity either benefits or thwarts sports-related performance.