First crack at exploring reported perf issues

See weavejester#226 (comment)

cljfmt/deps.edn

@@ -0,0 +1,4 @@
+{:paths ["src" "resources"]
+ :deps {org.clojure/clojure {:mvn/version "1.10.3"}
+        rewrite-clj/rewrite-clj {:mvn/version "1.0.605-alpha" }
+        criterium/criterium {:mvn/version "0.4.6"}}}

cljfmt/perf.clj

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+(ns perf
+  (:require [cljfmt.core :as cljfmt]
+            [criterium.core :as criterium]
+            [rewrite-clj.parser :as p]))
+
+(def sample1 "https://raw.githubusercontent.com/clojure-lsp/clojure-lsp/cd64d430d83cb068d4a0a011beeded3beb791201/src/clojure_lsp/handlers.clj")
+
+(defn -main [[test-id]]
+  (case test-id
+    "reformat-string"
+    (let [s (slurp sample1)]
+      (println "benchmarking reformat-string")
+      (criterium/with-progress-reporting (criterium/bench (cljfmt/reformat-string s) :verbose)))
+
+    "reformat-form"
+    (let [s (slurp sample1)
+          n (p/parse-string-all s)]
+      (println "benchmarking reformat-form")
+      (criterium/with-progress-reporting (criterium/bench (cljfmt/reformat-form n) :verbose)))))
+
+(-main *command-line-args*)