Question about clothing in martial arts.

In movies, shows and real life tournaments, I've seen fighters wearing light clothes. I've even seen men without shirts and shoes. I know that's for speed, but does it mean they can't be fast enough with heavy clothes? I mean, I've seen a few tokusatsu movies and shows where the choreography isn't as... "complex". Is it because the actors/stunt doubles are wearing super suits (specially the metallic ones)? What about masks and helmets? Those affect visibility, right?