diff --git a/README.md b/README.md
index 7d09a00..5c9708f 100644
--- a/README.md
+++ b/README.md
@@ -4,92 +4,128 @@ SharpEval is a library that allows you to parse & evaluate math expressions at r
 
 ## Features
 
-- Parses and evaluates expressions extremely fast.
-- Supports custom variables and functions.
-- Compatible with Unity 3.4.0 and newer.
-- Supports Unity IL2CPP.
-- No reflection.
-- No external dependencies.
+- Parses and evaluates expressions extremely fast
+- Supports custom variables and functions
+- Compatible with Unity 3.4.0 and newer
+- Supports Unity IL2CPP
+- No reflection
+- No external dependencies
 
 ## Usage
 
-- Parse & evaluate a simple expression:
+### Parse & evaluate a simple expression:
 
 ```cs
 using SharpEval;
+using SharpEval.Tokens;
 
 internal static class Program
 {
   internal static void Main()
   {
-    Console.WriteLine(Interpreter.ParseAndEvaluate(" 2 * ( 2 + 2 ) / 2 ")); // 4
+    IToken[] tokens = Tokenizer.Tokenize(" 2 * ( 2 + 2 ) / 2 ");
+  
+    Interpreter interpreter = new Interpreter();
+  
+    Console.WriteLine(interpreter.EvaluateExpression(tokens)); // 4
   }
 }
 ```
 
-- Parse & evaluate a more complex expression:
+### Parse & evaluate a more complex expression:
 
 ```cs
 using SharpEval;
+using SharpEval.Tokens;
 
 internal static class Program
 {
   internal static void Main()
   {
-    Console.WriteLine(Interpreter.ParseAndEvaluate(" ( ( ( 2 + 2 ) ^ 2 + 16 ) - 2 ^ ( 4 + 4 ) ) / 2")); // -112
+    IToken[] tokens = Tokenizer.Tokenize(" ( ( ( 2 + 2 ) ^ 2 + 16 ) - 2 ^ ( 4 + 4 ) ) / 2");
+  
+    Interpreter interpreter = new Interpreter();
+  
+    Console.WriteLine(interpreter.EvaluateExpression(tokens)); // -112
   }
 }
 ```
 
-- Define custom read-only variables:
+### Define custom read-only variables:
 
 ```cs
 using SharpEval;
+using SharpEval.Tokens;
+using SharpEval.Variables;
 
 internal static class Program
 {
   internal static void Main()
   {
-    Interpreter.Variables["x"] = new ReadOnlyVariable(10.0d);
-    Interpreter.Variables["y"] = new ReadOnlyVariable(15.0d);
+    IToken[] tokens = Tokenizer.Tokenize(" x + y ");
+    
+    Dictionary<string, IVariable> variables = new Dictionary<string, IVariable>()
+    {
+        ["x"] = new ReadOnlyVariable(10.0d),
+        ["y"] = new ReadOnlyVariable(20.0d),
+    };
     
-    Console.WriteLine(Interpreter.ParseAndEvaluate(" x + y ")); // 25
+    Interpreter interpreter = new Interpreter(variables: variables);
+    
+    Console.WriteLine(interpreter.EvaluateExpression(tokens)); // 25
   }
 }
 ```
 
-- Define custom computed variables:
+### Define custom computed variables:
 
 ```cs
 using SharpEval;
+using SharpEval.Tokens;
+using SharpEval.Variables;
 using System;
 
 internal static class Program
 {
   internal static void Main()
   {
-    var random = new Random();
+    IToken[] tokens = Tokenizer.Tokenize(" randomNumber + 1 ");
+    
+    Random random = new Random();
+    
+    Dictionary<string, IVariable> variables = new Dictionary<string, IVariable>()
+    {
+        ["randomNumber"] = new ComputedVariable(() => random.NextDouble()),
+    };
   
-    Interpreter.Variables["rnd"] = new ComputedVariable(() => random.NextDouble());
+    Interpreter interpreter = new Interpreter(variables: variables);
     
-    Interpreter.ParseAndEvaluate("rnd * 100.0d");
+    Console.WriteLine(interpreter.EvaluateExpression(tokens));
   }
 }
 ```
 
-- Define custom functions:
+### Define custom functions:
 
 ```cs
 using SharpEval;
+using SharpEval.Tokens;
 using System.Linq;
 
 internal static class Program
 {
   internal static void Main()
   {
-    Interpreter.Functions["sum"] = args => args.Sum();
+    IToken[] tokens = Tokenizer.Tokenize(" sum( 1, 2, 3 ) ");
+    
+    Dictionary<string, Func<double[], double>> functions = new Dictionary<string, Func<double[], double>>()
+    {
+        ["sum"] = args => args.Sum(),
+    };
+    
+    Interpreter interpreter = new Interpreter(functions: functions);
     
-    Console.WriteLine(Interpreter.ParseAndEvaluate(" sum ( 2 , 2 , 2 , 2 , 2 ) ")); // 10
+    Console.WriteLine(interpreter.EvaluateExpression(tokens)); // 6
   }
 }
 ```
diff --git a/src/SharpEval.Tests/UnitTest1.cs b/src/SharpEval.Tests/UnitTest1.cs
index 6927ce8..d1e8451 100644
--- a/src/SharpEval.Tests/UnitTest1.cs
+++ b/src/SharpEval.Tests/UnitTest1.cs
@@ -1,4 +1,6 @@
 using SharpEval.Tokens;
+using System.Diagnostics;
+using Xunit;
 using Xunit.Abstractions;
 
 namespace SharpEval.Tests;
@@ -12,18 +14,41 @@ public UnitTest1(ITestOutputHelper testOutputHelper)
 		_testOutputHelper = testOutputHelper;
 	}
 
-	private const string MathExpression = "-(2 + 2) - 4 * 8 / 4";
+	private const string MathExpression =
+		"( ( 2 + 2 ) / 2 - 8 * 4 + 16 + ( ( 2 + 2 ) / 2 - 8 * 4 + 16 ) + ( ( 2 + 2 ) / 2 - 8 * 4 + 16 + ( ( 2 + 2 ) / 2 - 8 * 4 + 16 ) + ( ( 2 + 2 ) / 2 - 8 * 4 + 16 ) ) ) + ( ( 2 + 2 ) / 2 - 8 * 4 + 16 + ( ( 2 + 2 ) / 2 - 8 * 4 + 16 ) + ( ( 2 + 2 ) / 2 - 8 * 4 + 16 + ( ( 2 + 2 ) / 2 - 8 * 4 + 16 ) + ( ( 2 + 2 ) / 2 - 8 * 4 + 16 ) ) ) + ( ( 2 + 2 ) / 2 - 8 * 4 + 16 + ( ( 2 + 2 ) / 2 - 8 * 4 + 16 ) + ( ( 2 + 2 ) / 2 - 8 * 4 + 16 + ( ( 2 + 2 ) / 2 - 8 * 4 + 16 ) + ( ( 2 + 2 ) / 2 - 8 * 4 + 16 ) ) ) + ( ( 2 + 2 ) / 2 - 8 * 4 + 16 + ( ( 2 + 2 ) / 2 - 8 * 4 + 16 ) + ( ( 2 + 2 ) / 2 - 8 * 4 + 16 + ( ( 2 + 2 ) / 2 - 8 * 4 + 16 ) + ( ( 2 + 2 ) / 2 - 8 * 4 + 16 ) ) ) + ( ( 2 + 2 ) / 2 - 8 * 4 + 16 + ( ( 2 + 2 ) / 2 - 8 * 4 + 16 ) + ( ( 2 + 2 ) / 2 - 8 * 4 + 16 + ( ( 2 + 2 ) / 2 - 8 * 4 + 16 ) + ( ( 2 + 2 ) / 2 - 8 * 4 + 16 ) ) ) + ( ( 2 + 2 ) / 2 - 8 * 4 + 16 + ( ( 2 + 2 ) / 2 - 8 * 4 + 16 ) + ( ( 2 + 2 ) / 2 - 8 * 4 + 16 + ( ( 2 + 2 ) / 2 - 8 * 4 + 16 ) + ( ( 2 + 2 ) / 2 - 8 * 4 + 16 ) ) ) + ( ( 2 + 2 ) / 2 - 8 * 4 + 16 + ( ( 2 + 2 ) / 2 - 8 * 4 + 16 ) + ( ( 2 + 2 ) / 2 - 8 * 4 + 16 + ( ( 2 + 2 ) / 2 - 8 * 4 + 16 ) + ( ( 2 + 2 ) / 2 - 8 * 4 + 16 ) ) ) + ( ( 2 + 2 ) / 2 - 8 * 4 + 16 + ( ( 2 + 2 ) / 2 - 8 * 4 + 16 ) + ( ( 2 + 2 ) / 2 - 8 * 4 + 16 + ( ( 2 + 2 ) / 2 - 8 * 4 + 16 ) + ( ( 2 + 2 ) / 2 - 8 * 4 + 16 ) ) )";
 
 	[Fact]
 	public void Test1()
 	{
 		IToken[] tokens = Tokenizer.Tokenize(MathExpression);
-
+		
 		foreach (IToken token in tokens)
 		{
 			_testOutputHelper.WriteLine(token.ToString());
 		}
 
-		Assert.Equal(new Interpreter().EvaluateExpression(tokens), -(2 + 2) - 4 * 8 / 4);
+		long min = long.MaxValue;
+		long max = long.MinValue;
+
+		Stopwatch stopwatch = new();
+
+		Interpreter interpreter = new();
+
+		double result = 0.0d;
+
+		for (int i = 0; i < 4_000; i++)
+		{
+			stopwatch.Restart();
+
+			result = interpreter.EvaluateExpression(tokens);
+
+			stopwatch.Stop();
+
+			if (stopwatch.ElapsedMilliseconds < min) min = stopwatch.ElapsedMilliseconds;
+
+			if (stopwatch.ElapsedMilliseconds > max) max = stopwatch.ElapsedMilliseconds;
+		}
+
+		_testOutputHelper.WriteLine($"Result: {result}, Took: {min}ms - {max}ms");
 	}
 }
diff --git a/src/SharpEval.Tests/Usings.cs b/src/SharpEval.Tests/Usings.cs
deleted file mode 100644
index c802f44..0000000
--- a/src/SharpEval.Tests/Usings.cs
+++ /dev/null
@@ -1 +0,0 @@
-global using Xunit;