The reason, in general: In a fossil+venti setup, fossil runs (basically) as a cache for venti. If your access just hits fossil, it’ll be quick; if not, you hit the (significantly slower) venti. I bet if you re-run the same test twice in a row, you’re going to see dramatically improved performance. Try it. If that’s true, the question is really one of venti performance; if not, you may have another system config issue.
There are various changes you can make to how venti uses disk/memory that can speed things up, but I don’t have a good handle on which to suggest first. Your write performance in that test isn’t really relevant: they’re not hitting the file system at all. I’m not sure why you’d see a difference in a fossil+venti setup of a different size, but the partition size relationships, and the in-memory cache size relationships, are what’s mostly important. a
