So, there's this function. It's called a lot. More importantly, all those calls are on the critical path of a key user interaction. Let's talk about making it fast. Spoiler: it's a dot product. Some background (or skip to the juicy stuff) At Sourcegraph, we're working on a Code AI tool named Cody. In order for Cody to answer questions well, we need to give them enough context to work with. One of