add invoke_single fast path for no-arg filter invocation, avoids splat alloc

lib/liquid/context.rb

@@ -109,6 +109,12 @@ module Liquid
       strainer.invoke(method, *args).to_liquid
     end
 
+    # Fast path for single-argument filter invocation (the most common case:
+    # {{ value | filter }}) — avoids *args splat allocation.
+    def invoke_single(method, input)
+      strainer.invoke_single(method, input).to_liquid
+    end
+
     # Push new local scope on the stack. use <tt>Context#stack</tt> instead
     def push(new_scope = {})
       @scopes.unshift(new_scope)

lib/liquid/strainer_template.rb

@@ -58,5 +58,19 @@ module Liquid
     rescue ::ArgumentError => e
       raise Liquid::ArgumentError, e.message, e.backtrace
     end
+
+    # Fast path for single-argument (no extra args) filter invocation.
+    # Avoids *args splat allocation for the common {{ value | filter }} case.
+    def invoke_single(method, input)
+      if self.class.invokable?(method)
+        send(method, input)
+      elsif @context.strict_filters
+        raise Liquid::UndefinedFilter, "undefined filter #{method}"
+      else
+        input
+      end
+    rescue ::ArgumentError => e
+      raise Liquid::ArgumentError, e.message, e.backtrace
+    end
   end
 end

lib/liquid/variable.rb

@@ -306,7 +306,7 @@ module Liquid
 
       @filters.each do |filter_name, filter_args, filter_kwargs|
         if filter_args.empty? && !filter_kwargs
-          obj = context.invoke(filter_name, obj)
+          obj = context.invoke_single(filter_name, obj)
         else
           filter_args = evaluate_filter_expressions(context, filter_args, filter_kwargs)
           obj = context.invoke(filter_name, obj, *filter_args)