diff --git a/interscript.gemspec b/interscript.gemspec
index 78e09f4c..ee445e14 100644
--- a/interscript.gemspec
+++ b/interscript.gemspec
@@ -35,5 +35,5 @@ Gem::Specification.new do |spec|
   spec.add_dependency "thor"
   spec.add_dependency "interscript-maps", "~> #{Interscript::VERSION.split(".")[0, 2].join(".")}.0a"
   spec.add_dependency "text"
-  spec.add_dependency "parslet", "~> 2.0"
+  spec.add_dependency "parsanol", "~> 1.3"
 end
diff --git a/lib/interscript/compiler.rb b/lib/interscript/compiler.rb
index 6b1a799a..7e8556bd 100644
--- a/lib/interscript/compiler.rb
+++ b/lib/interscript/compiler.rb
@@ -10,7 +10,7 @@ class Interscript::Compiler
 
   def self.call(map, **kwargs)
     # DSL.parse locates, dispatches .isc and caches the parsed document —
-    # calling parse_isc here re-ran a ~30 s Parslet parse on every
+    # calling parse_isc here re-ran a full grammar parse on every
     # compiler instantiation.
     map = Interscript::DSL.parse(map) if String === map
     compiler = new
diff --git a/lib/interscript/dsl.rb b/lib/interscript/dsl.rb
index b085b021..14f6de9f 100644
--- a/lib/interscript/dsl.rb
+++ b/lib/interscript/dsl.rb
@@ -40,7 +40,7 @@ def self.parse(map_name, reverse: true)
       end
     end
     # ISC documents route through the ISC parser, not the .imp DSL.
-    # The parse is expensive (Parslet over the whole map) — cache it like
+    # The parse is expensive (the whole grammar over the map) — cache it like
     # the .imp path does, or every transliterate call re-parses the map.
     return @cache[map_name] = Interscript::Compiler.parse_isc(path) if path.end_with?(".isc")
 
diff --git a/lib/interscript/isc.rb b/lib/interscript/isc.rb
index a1aeb766..ff3284eb 100644
--- a/lib/interscript/isc.rb
+++ b/lib/interscript/isc.rb
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require "parslet"
+require "parsanol"
 
 module Interscript
   module Isc
diff --git a/lib/interscript/isc/document_builder.rb b/lib/interscript/isc/document_builder.rb
index 886778b6..232ef42b 100644
--- a/lib/interscript/isc/document_builder.rb
+++ b/lib/interscript/isc/document_builder.rb
@@ -71,10 +71,12 @@ def build
       def unquote(fragment)
         return "" if fragment.nil?
         return fragment.to_s unless fragment.is_a?(Hash)
-        return fragment.to_s unless fragment.key?(:string)
+        # Direct decode for the overwhelmingly common shape — routing
+        # every quoted string through Transform pattern matching
+        # dominated large-map builds.
+        return Transform.decode_string_parts(fragment[:string]) if fragment.key?(:string)
 
-        out = @transform.apply(fragment)
-        out.is_a?(Items::StringValue) ? out.value : out.to_s
+        fragment.to_s
       end
 
       def unescape_braces(text)
@@ -325,17 +327,19 @@ def extract_dependency(item)
         }.compact
       end
 
-      # Convert a parslet tree fragment into a concrete Item object via Transform.
+      # Convert a grammar tree fragment into a concrete Item object via
+      # Transform. Reuses the builder's Transform instance — allocating
+      # one per fragment dominated large-map builds.
       def materialize(fragment)
         case fragment
         when Hash
           if fragment.key?(:concatenation)
-            Transform.new.apply(fragment)
+            @transform.apply(fragment)
           else
-            Transform.new.apply(concatenation: [fragment])
+            @transform.apply(concatenation: [fragment])
           end
         when Array
-          Transform.new.apply(concatenation: fragment)
+          @transform.apply(concatenation: fragment)
         when NilClass
           Items::None.new
         else
diff --git a/lib/interscript/isc/grammar.rb b/lib/interscript/isc/grammar.rb
index 7d0d1a37..a4f6ce3b 100644
--- a/lib/interscript/isc/grammar.rb
+++ b/lib/interscript/isc/grammar.rb
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require "parslet"
+require "parsanol"
 
 module Interscript
   module Isc
diff --git a/lib/interscript/isc/grammar/concerns/aliases.rb b/lib/interscript/isc/grammar/concerns/aliases.rb
index 0dd1fc03..c595ceda 100644
--- a/lib/interscript/isc/grammar/concerns/aliases.rb
+++ b/lib/interscript/isc/grammar/concerns/aliases.rb
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require "parslet"
+require "parsanol"
 
 module Interscript
   module Isc
@@ -8,7 +8,7 @@ module Grammar
       module Concerns
         # Aliases block: named expressions reused throughout the system.
         module Aliases
-          include Parslet
+          include Parsanol
 
           rule(:aliases_block) do
             str("aliases") >> whitespace? >>
diff --git a/lib/interscript/isc/grammar/concerns/dependencies.rb b/lib/interscript/isc/grammar/concerns/dependencies.rb
index c0e865b6..2c908dd4 100644
--- a/lib/interscript/isc/grammar/concerns/dependencies.rb
+++ b/lib/interscript/isc/grammar/concerns/dependencies.rb
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require "parslet"
+require "parsanol"
 
 module Interscript
   module Isc
@@ -8,7 +8,7 @@ module Grammar
       module Concerns
         # Dependencies: references to other systems whose stages may be invoked.
         module Dependencies
-          include Parslet
+          include Parsanol
 
           rule(:dependency_decl) do
             str("dependency") >> whitespace >>
diff --git a/lib/interscript/isc/grammar/concerns/items.rb b/lib/interscript/isc/grammar/concerns/items.rb
index 9ff16ff6..add11250 100644
--- a/lib/interscript/isc/grammar/concerns/items.rb
+++ b/lib/interscript/isc/grammar/concerns/items.rb
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require "parslet"
+require "parsanol"
 
 module Interscript
   module Isc
@@ -8,7 +8,7 @@ module Grammar
       module Concerns
         # Item expressions: the building blocks of rule matches and targets.
         module Items
-          include Parslet
+          include Parsanol
 
           rule(:item_atom) do
             quoted_string |
diff --git a/lib/interscript/isc/grammar/concerns/metadata.rb b/lib/interscript/isc/grammar/concerns/metadata.rb
index 5b4f8587..1b79aa45 100644
--- a/lib/interscript/isc/grammar/concerns/metadata.rb
+++ b/lib/interscript/isc/grammar/concerns/metadata.rb
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require "parslet"
+require "parsanol"
 
 module Interscript
   module Isc
@@ -8,7 +8,7 @@ module Grammar
       module Concerns
         # Metadata block: identity + provenance + lifecycle of a system.
         module Metadata
-          include Parslet
+          include Parsanol
 
           rule(:metadata_block) do
             str("metadata") >> whitespace? >>
diff --git a/lib/interscript/isc/grammar/concerns/primitives.rb b/lib/interscript/isc/grammar/concerns/primitives.rb
index befe7770..554cd5d5 100644
--- a/lib/interscript/isc/grammar/concerns/primitives.rb
+++ b/lib/interscript/isc/grammar/concerns/primitives.rb
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require "parslet"
+require "parsanol"
 
 module Interscript
   module Isc
@@ -9,7 +9,7 @@ module Concerns
         # Lexical primitives shared by every other concern.
         # Mirrors the structure of LutaML LML's Concerns::Primitives.
         module Primitives
-          include Parslet
+          include Parsanol
 
           # -- Whitespace and comments
 
@@ -74,9 +74,16 @@ module Primitives
           end
 
           # Double-quoted strings: \\uXXXX, \\n, etc. are interpreted.
+          # Escape-free stretches are captured as ONE run slice — a
+          # per-char capture allocates a hash + slice per character
+          # (~700k nodes for a large map) and the Transform pattern
+          # match grinds on them even under the native parse engine.
+          rule(:plain_run) do
+            (str("\\") | str('"')).absent? >> any
+          end
           rule(:double_quoted_string) do
             str('"') >>
-              (escape_sequence | (str('"').absent? >> any).as(:char)).repeat.as(:string) >>
+              (escape_sequence | plain_run.repeat(1).as(:run)).repeat.as(:string) >>
               str('"')
           end
 
diff --git a/lib/interscript/isc/grammar/concerns/stages.rb b/lib/interscript/isc/grammar/concerns/stages.rb
index 5838a386..70844407 100644
--- a/lib/interscript/isc/grammar/concerns/stages.rb
+++ b/lib/interscript/isc/grammar/concerns/stages.rb
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require "parslet"
+require "parsanol"
 
 module Interscript
   module Isc
@@ -8,7 +8,7 @@ module Grammar
       module Concerns
         # Stages: ordered transformation pipelines.
         module Stages
-          include Parslet
+          include Parsanol
 
           rule(:stage_block) do
             str("stage") >>
diff --git a/lib/interscript/isc/grammar/concerns/system.rb b/lib/interscript/isc/grammar/concerns/system.rb
index c3598c7a..7f51c9cb 100644
--- a/lib/interscript/isc/grammar/concerns/system.rb
+++ b/lib/interscript/isc/grammar/concerns/system.rb
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require "parslet"
+require "parsanol"
 
 module Interscript
   module Isc
@@ -8,7 +8,7 @@ module Grammar
       module Concerns
         # Top-level system block.
         module System
-          include Parslet
+          include Parsanol
 
           # A block-item is any of the top-level constructs that may appear
           # inside `system "<code>" { ... }`.
diff --git a/lib/interscript/isc/grammar/concerns/tests.rb b/lib/interscript/isc/grammar/concerns/tests.rb
index b49cad7f..5ffd1d84 100644
--- a/lib/interscript/isc/grammar/concerns/tests.rb
+++ b/lib/interscript/isc/grammar/concerns/tests.rb
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require "parslet"
+require "parsanol"
 
 module Interscript
   module Isc
@@ -8,7 +8,7 @@ module Grammar
       module Concerns
         # Tests block: normative input/output pairs.
         module Tests
-          include Parslet
+          include Parsanol
 
           rule(:tests_block) do
             str("tests") >> whitespace? >>
diff --git a/lib/interscript/isc/grammar/core.rb b/lib/interscript/isc/grammar/core.rb
index 790a553a..2ddfd8ed 100644
--- a/lib/interscript/isc/grammar/core.rb
+++ b/lib/interscript/isc/grammar/core.rb
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require "parslet"
+require "parsanol"
 
 module Interscript
   module Isc
@@ -8,7 +8,7 @@ module Grammar
       # Core grammar: composes every concern into a single Parser ancestor.
       # Mirrors the structure of LutaML LML's Grammar::Core.
       module Core
-        include Parslet
+        include Parsanol
         include Concerns::Primitives
         include Concerns::Items
         include Concerns::Metadata
diff --git a/lib/interscript/isc/parser.rb b/lib/interscript/isc/parser.rb
index 78c81d80..b0f551a1 100644
--- a/lib/interscript/isc/parser.rb
+++ b/lib/interscript/isc/parser.rb
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require "parslet"
+require "parsanol"
 
 module Interscript
   module Isc
@@ -11,7 +11,7 @@ module Isc
     #
     # The returned tree is a parslet-shaped hash — lists of hashes with
     # symbol keys. Convert to a domain object via Interscript::Isc::DocumentBuilder.
-    class Parser < Parslet::Parser
+    class Parser < Parsanol::Parser
       include Grammar::Core
 
       root :isc_source
@@ -22,7 +22,7 @@ def self.parse(source, filename: nil)
 
       def parse_with_callbacks(source, filename: nil)
         Normalizer.normalize(parse(source))
-      rescue Parslet::ParseFailed => e
+      rescue Parsanol::ParseFailed => e
         raise ParseError.new(e.message, filename: filename, source: source, cause: e)
       end
     end
diff --git a/lib/interscript/isc/transform.rb b/lib/interscript/isc/transform.rb
index c988dafa..2d5047e3 100644
--- a/lib/interscript/isc/transform.rb
+++ b/lib/interscript/isc/transform.rb
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require "parslet"
+require "parsanol"
 
 module Interscript
   module Isc
@@ -9,7 +9,7 @@ module Isc
     #
     # String escapes are unescaped here. Items are flattened. Constraints
     # are tagged by kind.
-    class Transform < Parslet::Transform
+    class Transform < Parsanol::Transform
       # String atom: parslet gives us a parslet slice for simple strings,
       # or an array of pieces (escape-sequence fragments interleaved with
       # raw chars) for strings containing escapes. Flatten both to a single
@@ -18,7 +18,7 @@ class Transform < Parslet::Transform
       rule(string: sequence(:parts)) do
         Items::StringValue.new(Transform.decode_string_parts(parts))
       end
-      rule(char: simple(:c)) { c.to_s }
+      rule(run: simple(:s)) { s.to_s }
 
       rule(identifier: simple(:i)) { i.to_s }
 
@@ -52,13 +52,13 @@ class Transform < Parslet::Transform
 
       # Shared decoder for the pieces of a :string capture — used by the
       # transform rules above and by the Normalizer's scalar folding. A
-      # fragment without an escape key is a raw character slice.
+      # fragment without an escape key is a raw run slice.
       def self.decode_string_parts(parts)
         Array(parts).map do |p|
           case p
           when Hash
-            if p.key?(:char)
-              p[:char].to_s
+            if p.key?(:run)
+              p[:run].to_s
             elsif p.key?(:newline)
               "\n"
             elsif p.key?(:carriage_return)