In previous work, we’ve argued that AI that can automate AI R&D could lead to a software intelligence explosion. But just how dramatic would this actually be? In this paper, we model how much AI progress we’ll see before a software intelligence explosion fizzles out. Averaged over one year, we find that AI progress could easily be 3X faster, might be 10X faster, but won’t be 30X faster - because at that speed we’d quickly hit limits on how good software can get.