diff --git a/CHANGELOG.md b/CHANGELOG.md
index c13bd55..704bc9e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Changed
 - Simplify string representation of mock-related types.
 - Remove unnecessary redefinitions of methods when adding stub functionality to a type.
+- Allow metadata to be stored as nil to reduce overhead when tracking nodes without tags.
 
 ## [0.11.4]
 ### Added
diff --git a/src/spectator/dsl/metadata.cr b/src/spectator/dsl/metadata.cr
index 308bcbd..04092b9 100644
--- a/src/spectator/dsl/metadata.cr
+++ b/src/spectator/dsl/metadata.cr
@@ -6,6 +6,9 @@ module Spectator::DSL
     private macro _spectator_metadata(name, source, *tags, **metadata)
       private def self.{{name.id}}
         %metadata = {{source.id}}.dup
+        {% unless tags.empty? && metadata.empty? %}
+          %metadata ||= ::Spectator::Metadata.new
+        {% end %}
         {% for k in tags %}
           %metadata[{{k.id.symbolize}}] = nil
         {% end %}
diff --git a/src/spectator/example.cr b/src/spectator/example.cr
index 3625ded..67483e0 100644
--- a/src/spectator/example.cr
+++ b/src/spectator/example.cr
@@ -40,7 +40,7 @@ module Spectator
     # Note: The metadata will not be merged with the parent metadata.
     def initialize(@context : Context, @entrypoint : self ->,
                    name : String? = nil, location : Location? = nil,
-                   @group : ExampleGroup? = nil, metadata = Metadata.new)
+                   @group : ExampleGroup? = nil, metadata = nil)
       super(name, location, metadata)
 
       # Ensure group is linked.
@@ -58,7 +58,7 @@ module Spectator
     # Note: The metadata will not be merged with the parent metadata.
     def initialize(@context : Context, @entrypoint : self ->,
                    @name_proc : Example -> String, location : Location? = nil,
-                   @group : ExampleGroup? = nil, metadata = Metadata.new)
+                   @group : ExampleGroup? = nil, metadata = nil)
       super(nil, location, metadata)
 
       # Ensure group is linked.
@@ -75,7 +75,7 @@ module Spectator
     # A set of *metadata* can be used for filtering and modifying example behavior.
     # Note: The metadata will not be merged with the parent metadata.
     def initialize(name : String? = nil, location : Location? = nil,
-                   @group : ExampleGroup? = nil, metadata = Metadata.new, &block : self ->)
+                   @group : ExampleGroup? = nil, metadata = nil, &block : self ->)
       super(name, location, metadata)
 
       @context = NullContext.new
@@ -93,9 +93,10 @@ module Spectator
     # A set of *metadata* can be used for filtering and modifying example behavior.
     # Note: The metadata will not be merged with the parent metadata.
     def self.pending(name : String? = nil, location : Location? = nil,
-                     group : ExampleGroup? = nil, metadata = Metadata.new, reason = nil)
+                     group : ExampleGroup? = nil, metadata = nil, reason = nil)
       # Add pending tag and reason if they don't exist.
-      metadata = metadata.merge({:pending => nil, :reason => reason}) { |_, v, _| v }
+      tags = {:pending => nil, :reason => reason}
+      metadata = metadata ? metadata.merge(tags) { |_, v, _| v } : tags
       new(name, location, group, metadata) { nil }
     end
 
diff --git a/src/spectator/example_builder.cr b/src/spectator/example_builder.cr
index bb640df..23398d2 100644
--- a/src/spectator/example_builder.cr
+++ b/src/spectator/example_builder.cr
@@ -15,7 +15,7 @@ module Spectator
     # The *entrypoint* indicates the proc used to invoke the test code in the example.
     # The *name*, *location*, and *metadata* will be applied to the `Example` produced by `#build`.
     def initialize(@context_builder : -> Context, @entrypoint : Example ->,
-                   @name : String? = nil, @location : Location? = nil, @metadata : Metadata = Metadata.new)
+                   @name : String? = nil, @location : Location? = nil, @metadata : Metadata? = nil)
     end
 
     # Creates the builder.
@@ -24,7 +24,7 @@ module Spectator
     # The *name* is an interpolated string that runs in the context of the example.
     # *location*, and *metadata* will be applied to the `Example` produced by `#build`.
     def initialize(@context_builder : -> Context, @entrypoint : Example ->,
-                   @name : Example -> String, @location : Location? = nil, @metadata : Metadata = Metadata.new)
+                   @name : Example -> String, @location : Location? = nil, @metadata : Metadata? = nil)
     end
 
     # Constructs an example with previously defined attributes and context.
diff --git a/src/spectator/example_group.cr b/src/spectator/example_group.cr
index dc1fa57..277be3c 100644
--- a/src/spectator/example_group.cr
+++ b/src/spectator/example_group.cr
@@ -79,7 +79,7 @@ module Spectator
     # This group will be assigned to the parent *group* if it is provided.
     # A set of *metadata* can be used for filtering and modifying example behavior.
     def initialize(@name : Label = nil, @location : Location? = nil,
-                   @group : ExampleGroup? = nil, @metadata : Metadata = Metadata.new)
+                   @group : ExampleGroup? = nil, @metadata : Metadata? = nil)
       # Ensure group is linked.
       group << self if group
     end
diff --git a/src/spectator/example_group_builder.cr b/src/spectator/example_group_builder.cr
index 05c740f..207cb6e 100644
--- a/src/spectator/example_group_builder.cr
+++ b/src/spectator/example_group_builder.cr
@@ -28,7 +28,7 @@ module Spectator
     # Creates the builder.
     # Initially, the builder will have no children and no hooks.
     # The *name*, *location*, and *metadata* will be applied to the `ExampleGroup` produced by `#build`.
-    def initialize(@name : Label = nil, @location : Location? = nil, @metadata : Metadata = Metadata.new)
+    def initialize(@name : Label = nil, @location : Location? = nil, @metadata : Metadata? = nil)
     end
 
     # Constructs an example group with previously defined attributes, children, and hooks.
diff --git a/src/spectator/example_group_iteration.cr b/src/spectator/example_group_iteration.cr
index d6576d2..0d20a29 100644
--- a/src/spectator/example_group_iteration.cr
+++ b/src/spectator/example_group_iteration.cr
@@ -18,7 +18,7 @@ module Spectator
     # This group will be assigned to the parent *group* if it is provided.
     # A set of *metadata* can be used for filtering and modifying example behavior.
     def initialize(@item : T, name : Label = nil, location : Location? = nil,
-                   group : ExampleGroup? = nil, metadata : Metadata = Metadata.new)
+                   group : ExampleGroup? = nil, metadata : Metadata? = nil)
       super(name, location, group, metadata)
     end
   end
diff --git a/src/spectator/iterative_example_group_builder.cr b/src/spectator/iterative_example_group_builder.cr
index 39ad549..fe67c7a 100644
--- a/src/spectator/iterative_example_group_builder.cr
+++ b/src/spectator/iterative_example_group_builder.cr
@@ -15,7 +15,7 @@ module Spectator
     # The *collection* is the set of items to create sub-nodes for.
     # The *iterators* is a list of optional names given to items in the collection.
     def initialize(@collection : Enumerable(T), name : String? = nil, @iterators : Array(String) = [] of String,
-                   location : Location? = nil, metadata : Metadata = Metadata.new)
+                   location : Location? = nil, metadata : Metadata? = nil)
       super(name, location, metadata)
     end
 
diff --git a/src/spectator/node.cr b/src/spectator/node.cr
index 807c8df..6a5d068 100644
--- a/src/spectator/node.cr
+++ b/src/spectator/node.cr
@@ -30,14 +30,16 @@ module Spectator
     end
 
     # User-defined tags and values used for filtering and behavior modification.
-    getter metadata : Metadata
+    def metadata : Metadata
+      @metadata ||= Metadata.new
+    end
 
     # Creates the node.
     # The *name* describes the purpose of the node.
     # It can be a `Symbol` to describe a type.
     # The *location* tracks where the node exists in source code.
     # A set of *metadata* can be used for filtering and modifying example behavior.
-    def initialize(@name : Label = nil, @location : Location? = nil, @metadata : Metadata = Metadata.new)
+    def initialize(@name : Label = nil, @location : Location? = nil, @metadata : Metadata? = nil)
     end
 
     # Indicates whether the node has completed.
@@ -46,17 +48,25 @@ module Spectator
     # Checks if the node has been marked as pending.
     # Pending items should be skipped during execution.
     def pending?
-      metadata.has_key?(:pending) || metadata.has_key?(:skip)
+      return false unless md = @metadata
+
+      md.has_key?(:pending) || md.has_key?(:skip)
     end
 
     # Gets the reason the node has been marked as pending.
     def pending_reason
-      metadata[:pending]? || metadata[:skip]? || metadata[:reason]? || DEFAULT_PENDING_REASON
+      return DEFAULT_PENDING_REASON unless md = @metadata
+
+      md[:pending]? || md[:skip]? || md[:reason]? || DEFAULT_PENDING_REASON
     end
 
     # Retrieves just the tag names applied to the node.
     def tags
-      Tags.new(metadata.keys)
+      if md = @metadata
+        Tags.new(md.keys)
+      else
+        Tags.new
+      end
     end
 
     # Non-nil name used to show the node name.
diff --git a/src/spectator/pending_example_builder.cr b/src/spectator/pending_example_builder.cr
index a1f0292..434efe5 100644
--- a/src/spectator/pending_example_builder.cr
+++ b/src/spectator/pending_example_builder.cr
@@ -11,7 +11,7 @@ module Spectator
     # The *name*, *location*, and *metadata* will be applied to the `Example` produced by `#build`.
     # A default *reason* can be given in case the user didn't provide one.
     def initialize(@name : String? = nil, @location : Location? = nil,
-                   @metadata : Metadata = Metadata.new, @reason : String? = nil)
+                   @metadata : Metadata? = nil, @reason : String? = nil)
     end
 
     # Constructs an example with previously defined attributes.
diff --git a/src/spectator/spec_builder.cr b/src/spectator/spec_builder.cr
index 265b41d..17b0284 100644
--- a/src/spectator/spec_builder.cr
+++ b/src/spectator/spec_builder.cr
@@ -60,7 +60,7 @@ module Spectator
     #
     # A set of *metadata* can be used for filtering and modifying example behavior.
     # For instance, adding a "pending" tag will mark tests as pending and skip execution.
-    def start_group(name, location = nil, metadata = Metadata.new) : Nil
+    def start_group(name, location = nil, metadata = nil) : Nil
       Log.trace { "Start group: #{name.inspect} @ #{location}; metadata: #{metadata}" }
       builder = ExampleGroupBuilder.new(name, location, metadata)
 
@@ -86,7 +86,7 @@ module Spectator
     #
     # A set of *metadata* can be used for filtering and modifying example behavior.
     # For instance, adding a "pending" tag will mark tests as pending and skip execution.
-    def start_iterative_group(collection, name, iterator = nil, location = nil, metadata = Metadata.new) : Nil
+    def start_iterative_group(collection, name, iterator = nil, location = nil, metadata = nil) : Nil
       Log.trace { "Start iterative group: #{name} (#{typeof(collection)}) @ #{location}; metadata: #{metadata}" }
       builder = IterativeExampleGroupBuilder.new(collection, name, iterator, location, metadata)
 
@@ -127,7 +127,7 @@ module Spectator
     # It will be yielded two arguments - the example created by this method, and the *context* argument.
     # The return value of the block is ignored.
     # It is expected that the test code runs when the block is called.
-    def add_example(name, location, context_builder, metadata = Metadata.new, &block : Example -> _) : Nil
+    def add_example(name, location, context_builder, metadata = nil, &block : Example -> _) : Nil
       Log.trace { "Add example: #{name} @ #{location}; metadata: #{metadata}" }
       current << ExampleBuilder.new(context_builder, block, name, location, metadata)
     end
@@ -144,7 +144,7 @@ module Spectator
     # A set of *metadata* can be used for filtering and modifying example behavior.
     # For instance, adding a "pending" tag will mark the test as pending and skip execution.
     # A default *reason* can be given in case the user didn't provide one.
-    def add_pending_example(name, location, metadata = Metadata.new, reason = nil) : Nil
+    def add_pending_example(name, location, metadata = nil, reason = nil) : Nil
       Log.trace { "Add pending example: #{name} @ #{location}; metadata: #{metadata}" }
       current << PendingExampleBuilder.new(name, location, metadata, reason)
     end
diff --git a/src/spectator/tag_node_filter.cr b/src/spectator/tag_node_filter.cr
index d360712..0dedd59 100644
--- a/src/spectator/tag_node_filter.cr
+++ b/src/spectator/tag_node_filter.cr
@@ -10,7 +10,9 @@ module Spectator
 
     # Checks whether the node satisfies the filter.
     def includes?(node) : Bool
-      node.metadata.any? { |key, value| key.to_s == @tag && (!@value || value == @value) }
+      return false unless metadata = node.metadata
+
+      metadata.any? { |key, value| key.to_s == @tag && (!@value || value == @value) }
     end
   end
 end
diff --git a/src/spectator/test_context.cr b/src/spectator/test_context.cr
index a68c5b9..e04fe56 100644
--- a/src/spectator/test_context.cr
+++ b/src/spectator/test_context.cr
@@ -34,7 +34,7 @@ class SpectatorTestContext < SpectatorContext
 
   # Initial metadata for tests.
   # This method should be overridden by example groups and examples.
-  private def self.metadata
-    ::Spectator::Metadata.new
+  private def self.metadata : ::Spectator::Metadata?
+    nil
   end
 end