Here are all our issues that track performance: https://github.com/cockroachdb/cockroach/issues?utf8=%E2%9C%...
Here’s our open source repository where we keep our load generators: https://github.com/cockroachdb/loadgen
A blog post (well, many) are in the works outlining our performance benchmarking. The situation on the ground is changing fast - our performance has improved rapidly over the past months, and each time we sit down to write a blog post, it gets quickly obsoleted. So, trust that we will have a blog post talking about performance very soon.
Anecdotally, our customers are not finding performance to be a bottleneck. I encourage you to set up a Cockroach cluster, and try the various load generators (we've got the standards and a couple other homegrown ones in the repository).