diff --git a/Library/Homebrew/formulary.rb b/Library/Homebrew/formulary.rb
index 1a882e18d2..90fb41557b 100644
--- a/Library/Homebrew/formulary.rb
+++ b/Library/Homebrew/formulary.rb
@@ -1201,7 +1201,6 @@ module Formulary
       "#{name}.rb"
     end
 
-    Tap.formula_files_by_name(tap)
-       .fetch(name, tap.formula_dir/filename)
+    tap.formula_files_by_name.fetch(name, tap.formula_dir/filename)
   end
 end
diff --git a/Library/Homebrew/tap.rb b/Library/Homebrew/tap.rb
index 0d59ec16e3..256816d647 100644
--- a/Library/Homebrew/tap.rb
+++ b/Library/Homebrew/tap.rb
@@ -128,6 +128,7 @@ class Tap
     @command_dir = nil
     @formula_names = nil
     @formula_files = nil
+    @formula_files_by_name = nil
     @cask_files = nil
     @cask_files_by_name = nil
     @alias_dir = nil
@@ -561,19 +562,12 @@ class Tap
     end
   end
 
-  # A cached hash of {Formula} basenames to {Formula} file pathnames for a {Tap}
-  sig { params(tap: Tap).returns(T::Hash[String, Pathname]) }
-  def self.formula_files_by_name(tap)
-    cache_key = "formula_files_by_name_#{tap}"
-    cache.fetch(cache_key) do |key|
-      cache[key] = tap.formula_files_by_name
-    end
-  end
-
+  # A mapping of {Formula} names to {Formula} file paths.
+  #
   # @private
   sig { returns(T::Hash[String, Pathname]) }
   def formula_files_by_name
-    formula_files.each_with_object({}) do |file, hash|
+    @formula_files_by_name ||= formula_files.each_with_object({}) do |file, hash|
       # If there's more than one file with the same basename: use the longer one to prioritise more specific results.
       basename = file.basename(".rb").to_s
       existing_file = hash[basename]