diff --git a/StandardLibrary/test/TestMutableMap.dfy b/StandardLibrary/test/TestMutableMap.dfy
new file mode 100644
index 000000000..67c6dca74
--- /dev/null
+++ b/StandardLibrary/test/TestMutableMap.dfy
@@ -0,0 +1,74 @@
+include "../../libraries/src/MutableMap/MutableMap.dfy"
+include "../../StandardLibrary/src/Index.dfy"
+
+module TestMutableMap {
+  import opened DafnyLibraries
+  import opened StandardLibrary.UInt
+  import Time
+
+  method {:test} TestPerformanceScaling()
+  {
+    var sizes := [1, 10, 10000, 100000, 1000000, 1000000000, 100000000000000000];
+    var i := 0;
+    while i < |sizes| {
+        TestForEachSize(sizes[i]);
+        i := i + 1;
+    }
+  }
+
+  method TestForEachSize(size: int)
+    requires size > 0
+  {
+    var time1 := Time.GetAbsoluteTime();
+    TestMapOperations(size);
+    print "Time taken for " , size , " items \n";
+    Time.PrintTimeSince(time1);
+  }
+
+  method TestMapOperations(size: int)
+  requires size > 0
+{
+  // Explicitly parametrize with <seq<uint8>, int>
+  var testMap := new MutableMap((k: seq<uint8>, v: int) => true, true);
+  var i := 0;
+  while i < size {
+    // Convert int -> seq<uint8> (just an example: single-byte sequence)
+    var key := IntToBytes(i); 
+    testMap.Put(key, i);
+    i := i + 1;
+  }
+  expect testMap.Size() == size;
+  // Reset loop
+  i := 0;
+  while i < size {
+    var key := IntToBytes(i);
+    var tempI := testMap.Select(key);
+    expect i == tempI;
+    i := i + 1;
+  }
+  i := 0;
+  while i < size {
+    var key := IntToBytes(i);
+    testMap.Remove(key);
+    expect !testMap.HasKey(key);
+    i := i + 1;
+  }
+}
+method IntToBytes(x: int) returns (bytes: seq<uint8>)
+  requires x >= 0
+  ensures |bytes| > 0
+{
+  var result := [];
+  var n := x;
+  while n > 0
+    decreases n
+  {
+    result := [(n % 256) as uint8] + result;
+    n := n / 256;
+  }
+  if |result| == 0 {
+    result := [(0) as uint8];
+  }
+  bytes := result;
+}
+}