diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..89af941
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,7 @@
+test :
+	node speci.js x-first
+	node speci.js y-first
+	node speci.js mixed
+	node speci.js rand-suffix
+	node speci.js rand-prefix
+
diff --git a/readme.md b/readme.md
index 81dd0d4..d2c0880 100644
--- a/readme.md
+++ b/readme.md
@@ -9,44 +9,59 @@ handle a couple of different variants -- but this might not be true of all
 possibilities. 256 randomized variants is linearly slower.
 
 ```
- % node speci.js
-** x_first
+% make test
+node speci.js x-first
+** x-first
 run 1
-72 ms
+189 ms
 
 run 2
-15 ms
+293 ms
 
 run 3
-22 ms
+178 ms
 
-** y_first
+node speci.js y-first
+** y-first
 run 1
-73 ms
+196 ms
 
 run 2
-23 ms
+175 ms
 
 run 3
-20 ms
+174 ms
 
+node speci.js mixed
 ** mixed
 run 1
-2766 ms
+732 ms
 
 run 2
-52 ms
+716 ms
 
 run 3
-53 ms
+912 ms
 
-** randomized
+node speci.js rand-suffix
+** rand-suffix
 run 1
-464 ms
+15596 ms
 
 run 2
-445 ms
+15636 ms
 
 run 3
-445 ms
+15501 ms
+
+node speci.js rand-prefix
+** rand-prefix
+run 1
+18896 ms
+
+run 2
+18883 ms
+
+run 3
+18784 ms
 ```
diff --git a/speci.js b/speci.js
index 3b31dcf..8cf3b0d 100644
--- a/speci.js
+++ b/speci.js
@@ -1,4 +1,4 @@
-function doit() {
+function doit(mode) {
 
     function make_x_first(x,y) {
         return {x, y};
@@ -16,23 +16,23 @@ function doit() {
         }
     }
 
-    function make_randomized(x, y) {
+    function make_rand_prefix(x, y) {
         let rando = (Math.random() * (2 ** 32 - 1)) | 0;
-        let buckets = 256;
-        let r = 'random' + (rando % buckets);
-        let o = {[r]: r};
-        if (Math.random() > 0.5) {
-            o.y = y;
-            o.x = x;
-        } else {
-            o.x = x;
-            o.y = y;
-        }
+        let r = 'random' + rando;
+        let o = {[r]: r, x, y};
+        return o;
+    }
+
+    function make_rand_suffix(x, y) {
+        let rando = (Math.random() * (2 ** 32 - 1)) | 0;
+        let r = 'random' + rando;
+        let o = {x, y, [r]: r};
         return o;
     }
 
     const million = 1000 * 1000;
-    const n = 10 * million;
+    const n = 1 * million;
+    const runs = 100 * n;
 
     function bulk(filler) {
         let a = [];
@@ -42,10 +42,22 @@ function doit() {
         return a;
     }
 
-    const x_first = bulk(make_x_first);
-    const y_first = bulk(make_y_first);
-    const mixed = bulk(make_mixed);
-    const randomized = bulk(make_randomized);
+    let funcMap = {
+        'x-first': make_x_first,
+        'y-first': make_y_first,
+        'mixed': make_mixed,
+        'rand-prefix': make_rand_prefix,
+        'rand-suffix': make_rand_suffix,
+    };
+    let func = funcMap[mode];
+    if (!func) {
+        console.log(`Pass as parameter one of:`);
+        for (let key of Object.keys(funcMap)) {
+            console.log(`  ${key}`);
+        }
+        process.exit(1);
+    }
+    const data = bulk(func);
 
     function time(func) {
         const start = Date.now();
@@ -64,8 +76,8 @@ function doit() {
             console.log(`run ${i+1}`);
             report(() => {
                 let sumX = 0, sumY = 0;
-                for (let i = 0; i < dataSet.length; i++) {
-                    let item = dataSet[i];
+                for (let i = 0; i < runs; i++) {
+                    let item = dataSet[i % dataSet.length];
                     sumX += item.x;
                     sumY += item.y;
                 }
@@ -75,18 +87,9 @@ function doit() {
         }
     }
 
-    console.log(`** x_first`);
-    demo(x_first);
-
-    console.log(`** y_first`);
-    demo(y_first);
-
-    console.log(`** mixed`);
-    demo(mixed);
-
-    console.log(`** randomized`);
-    demo(randomized);
-
+    console.log(`** ${mode}`);
+    demo(data);
 }
 
-doit();
\ No newline at end of file
+let mode = String(process.argv[2]);
+doit(mode);
\ No newline at end of file