diff --git a/test/StressTest.re b/test/StressTest.re
new file mode 100644
index 0000000..c8192e8
--- /dev/null
+++ b/test/StressTest.re
@@ -0,0 +1,97 @@
+open TestFramework;
+open Vim;
+
+let resetBuffer = () => Helpers.resetBuffer("test/testfile.txt");
+
+describe("Stress", ({describe, _}) => {
+  describe("Stress with undo lots of lines", ({test, _}) => {
+    test("Add and remove 1 million lines", ({expect}) => {
+      let initialBuffer = resetBuffer();
+      expect.int(Buffer.getLineCount(initialBuffer)).toBe(3);
+      let buffer = Buffer.openFile("test/lines_100.txt");
+      expect.int(Buffer.getLineCount(buffer)).toBe(100);
+
+      // Now lets duplicate the buffer a bunch.
+      input("yG");
+      input("9999p");
+
+      expect.int(Buffer.getLineCount(buffer)).toBe(1000000);
+
+      input("u");
+
+      expect.int(Buffer.getLineCount(buffer)).toBe(100);
+    });
+
+    test("Add and remove 3 million lines", ({expect}) => {
+      let initialBuffer = resetBuffer();
+      expect.int(Buffer.getLineCount(initialBuffer)).toBe(3);
+      let buffer = Buffer.openFile("test/lines_100.txt");
+      expect.int(Buffer.getLineCount(buffer)).toBe(100);
+
+      // Now lets duplicate the buffer a bunch.
+      input("yG");
+      input("29999p");
+
+      expect.int(Buffer.getLineCount(buffer)).toBe(3000000);
+
+      input("u");
+
+      expect.int(Buffer.getLineCount(buffer)).toBe(100);
+    });
+
+    test("Add and remove 6 million lines", ({expect}) => {
+      let initialBuffer = resetBuffer();
+      expect.int(Buffer.getLineCount(initialBuffer)).toBe(3);
+      let buffer = Buffer.openFile("test/lines_100.txt");
+      expect.int(Buffer.getLineCount(buffer)).toBe(100);
+
+      // Now lets duplicate the buffer a bunch.
+      input("yG");
+      input("59999p");
+
+      expect.int(Buffer.getLineCount(buffer)).toBe(6000000);
+
+      input("u");
+
+      expect.int(Buffer.getLineCount(buffer)).toBe(100);
+    });
+    // test("Add and remove 10 million lines", ({expect}) => {
+    //   let initialBuffer = resetBuffer();
+    //   expect.int(Buffer.getLineCount(initialBuffer)).toBe(3);
+    //   let buffer = Buffer.openFile("test/lines_100.txt");
+    //   expect.int(Buffer.getLineCount(buffer)).toBe(100);
+    //   // Now lets duplicate the buffer a bunch.
+    //   input("yG");
+    //   input("99999p");
+    //   expect.int(Buffer.getLineCount(buffer)).toBe(10000000);
+    //   input("u");
+    //   expect.int(Buffer.getLineCount(buffer)).toBe(100);
+    // });
+  });
+
+  describe("Stress with large macros", ({test, _}) =>
+    test("Macro over 100 thousand lines", ({expect}) => {
+      let initialBuffer = resetBuffer();
+      expect.int(Buffer.getLineCount(initialBuffer)).toBe(3);
+      let buffer = Buffer.openFile("test/lines_100.txt");
+      expect.int(Buffer.getLineCount(buffer)).toBe(100);
+
+      // Now lets duplicate the buffer a bunch.
+      input("yG");
+      input("999p");
+
+      expect.int(Buffer.getLineCount(buffer)).toBe(100000);
+
+      // Reset the cursor and then record a macro
+      input("gg");
+      input("0");
+      input("qacwMyNewLine");
+      input("<esc>");
+      input("j0q");
+      input("99999@a");
+
+      let line = Buffer.getLine(buffer, 100000);
+      expect.string(line).toEqual("MyNewLine 100");
+    })
+  );
+});
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