lein cljsbuild once runs slowly

project.clj

(def cljs-files ["main" "template"])

(defn keyword-dasherize [& words]
  (keyword (clojure.string/join "-" words)))

(defn name-to-build-opts [name]
  {(keyword-dasherize name "dev")
   {:source-path (str "src/cljs-" name)
    :compiler
    {:output-to (str "resources/public/js/bin-debug-" name "/" name ".js")
     :output-dir (str "resources/public/js/bin-debug-" name)
     :optimizations :whitespace
     :pretty-print true}}
   (keyword-dasherize name "prod")
   {:source-path (str "src/cljs-" name)
    :compiler
    {:output-to (str "resources/public/js/bin/" name ".js")
     :output-dir (str "resources/public/js/bin-" name)
     :optimizations :whitespace
     :pretty-print true}}})

(def build-opts (apply merge (map name-to-build-opts cljs-files)))

(defproject papyrus "0.1.0-SNAPSHOT"
            :description "FIXME: write this!"
            :min-lein-version "2.0.0"
            :dependencies [[org.clojure/clojure "1.4.0"]
                           [jayq "2.0.0"]
                           [cc.qbits/fetch "0.1.0-alpha2"]
                           [crate "0.2.3"]
                           [clj-aws-s3 "0.3.3"]
                           [clj-pdf "1.0.5"]
                           [noir "1.3.0-beta10"]]
            :plugins [[lein-cljsbuild "0.2.10"]]
            :cljsbuild {:builds ~build-opts}
            :s3 {:bucket "papyrus-app"
                 :root "resources/public/"
                 :files ["js/bin/main.js" "js/bin/template.js"
                         "css/styles.css" "img/loading.gif"]}
            :main papyrus.server)