When people have limited time for a presentation they often start to cut "the meat" of the story. What's left after the trimming is a set of generic "summary slides" at such a high level of abstraction that they don't say very much anymore.
Venture capitalists do not have much time. Still, resist the temptation to skip the technology section when pitching your startup. This is the key asset you have. This is what makes you stand out from the competition. This is what makes VCs understand that there is a real business here, not just a set of PowerPoint slides.
How can you present a complex technology in very little time? Don't spend time on exhaustive architecture diagrams with layers of details and boring process flows. Instead make people understand why your technology is so unique and so hard to copy.
The deep dive is a good technique to do this. Take a few very specific examples, and dive all the way down into the detail to make your point. Show the complex code, show how long it took you to solve the issue, and show how it will take the competition double this time to imitate it.
Remember, your audience is smart (and busy). Any scientist or engineer should be able to explain the technology solution to an intelligent layman in just a few words and a few images. There is no bigger offense to your audience (and a guaranteed VC turn-off) then to say "this might be a bit too complicated for you, I'll just skip it in this executive summary".