Denver takes 264 days to approve "multi-family or industrial projects with a valuation in excess of $1.5 million, such as a new apartment or office building, large additions" [1]. Construction loans in Colorado cost "8% to 13%" [2]. For a project with $1.5mm up-front costs, from land purchases to permit fees and legal costs, that comes to $87 to 141 thousand per project.
This isn't as bad as San Francisco, where permiting delays alone add hundreds of thousands of dollars to housing costs. But in addition to upzoning, it's something to be considered, particularly since Denver seems to categorise practically all impactful residential development as "major commercial."
[1] https://www.denvergov.org/Government/Agencies-Departments-Of...
[2] https://www.clearhouselending.com/commercial-loans/colorado/...