I work in the tech industry. Started job hunting 4 months ago. Three companies (all startups) wanted me to do a technical presentation before the interview. I accepted (huge mistake!).
The presentation to the first company was received poorly. None of the interviewers actually paid attention to the presentation. I knew this because they kept asking the stuff that I had already explained. I was rejected later because I was “over quilified”.
The presentation to the second and third company went well at first. After a few questions from them, I started to realize that they were using me as a consultant because clearly they didn't know what they were talking about and wanted me to help solve their engineering problems. I was later rejected and they didn't reply any of my email since then.
In short, I would suggest avoid presenting anything before interviews. It seems to me companies who ask you to present are not seriously looking to hire… Plus it will make you feel like a fool after spending tremendous amount of time on a presentation and then get nothing in return.