We’re talking about people reacting to marketing text, so it’s all subjective. The way I see it, all software is as fast as possible, barring constraints which include the skills, priorities, and available effort of the software authors.
So if you want to mention in marketing text (which includes 1-liners at the top of a README) something about performance, you should be highlighting what sets the software apart from its peers. Is it because you use GPU acceleration where other projects don’t? Is it because you are using novel data structures and algorithms, or an interesting way of designing the software? Did you make different tradeoffs that led to performance being prioritized? Is it because the project authors have relevant experience, making them especially skilled at performance optimizations?
To me, slapping “blazing fast” into the elevator pitch without any further details tells me that the author didn’t give it much thought.
I think your two examples do slightly better:
- The Ghostty example also mentions rationale: GPU accelerated. It doesn’t mention what sets it apart from other projects which also do that, however.
- The Bun example puts the emphasis on “fast”. It communicates that the entire purpose of the project is to be a fast alternative to a specific existing technology.
In non-marketing text, I think we should strive to be more specific. “fast”, “bad”, “good”, are not useful words for engineers. We should say things with more details, such as “under conditions X, the software has Y performance characteristics” or “handles use cases A, B, C without common bugs in other software X, Y, Z”.
An exercise I like to do, when I find myself tempted to write comments complaining about the behavior of APIs or other software, is to write my complaint using facts only. So for example, instead of writing:
// recvmmsg sucks so we have to use recvmsg here
This is better:
// recvmmsg checks the timeout after making blocking calls to recvmsg, which
// means the timeout fails to interrupt the call, making recvmmsg useless here
Notice that if someone disagrees with the former example, we’re going to have an argument about whose opinions are better. On the other hand if someone disagrees with the latter example, it’s going to lead to improved code.
I see a lot of sloppy comments and commit messages of the former style in the Linux kernel for example, including many by Linus himself. I think that community in particular could benefit from this style of technical writing.