I think it's much less about sex than you think. From my experience, groups of all men and groups of all women are much less productive than a mixed group. "Sexual tension" is a factor in mixed groups, but so is any other kind of conflict.
The following is just my experience and I don't claim to generalize although I will use it as a generalization since it is what I have observed.
Groups of men tend to fall into a pattern. There is a leader, there are people vying to be the leader, and there are "subordinates" who execute directives. Male groups try and get something done. These groups are about organizing people.
Groups of women also fall into a pattern. They tend to plan and analyze and put less priority on execution. In female groups the leader/subordinate dynamic is much less apparent, and it's mostly a dance of trying to understand what everyone is saying and what everyone wants. These groups are about organizing ideas.
Mixed groups obviously have a mix of these approaches. Men and women help each other to reach a balanced state of execution and planning, looking at the details while also keeping the big picture in mind. In addition to that, mixed groups are way more dynamic and adaptable. Patterns emerge contextually within the group, rather than following a standard social protocol. To me, this indicates higher potential for productivity in all areas of a project.
Sexual tension can occur, but I think it's a bit silly to suggest it's a Big Deal in the workplace, that it's something significant enough to single out from every other messy thing that can happen in groups of people. To make myself clear, sexual tension is a separate thing from sexual harassment, which is definitely a problem but is the result of some bad players and not the mixed group dynamic itself.