That is a bit misleading. Yes Clojure starts in less than a second but then you add
core.async which adds another 500ms and so on. It is very easy to get past the 1 second mark with very few actual deps.
boot do add overhead yes but not significantly more than other libs.
One major thing that can contribute to startup time is having a
user.clj in your classpath which actually loads many deps. This file will be loaded whenever Clojure starts so even if you run something via
clj that doesn’t use the
user ns the deps will be loaded regardless making it appear slower than it needs to be. Many projects have a
user.clj with a generated set of REPL helper functions (eg.
start-figwheel). This means whatever you are running will always load everything CLJS+figwheel and so on making things very slow.
Make sure you have no
user.clj on the classpath if you intend to do lots of scripting.