Benchmark: Loop Optimization

Loop Optimization (version: 0)

Checking differences between various for/while loops.

Comparing performance of: For loop, basic vs While loop, basic vs For loop, cached (inside for statement) vs For loop, cached (outside for statement) vs For loop, i-- (caching inside for loop) vs For loop, i-- (caching outside for loop) vs While loop, cached vs While loop, i--

Created: 6 years ago by: Guest

Jump to the latest result

Script Preparation code:

  var arr = [];
  for (var i = 0; i < 1000; i++) {
    arr[i] = i;
  }

  function someFn(ix) {
    return ix * 5 + 1 / 3 * 8;
  }

Tests:

For loop, basic
for (var i = 0; i < arr.length; i++) { someFn(arr[i]); }
While loop, basic
var i = 0; while (i < arr.length) { someFn(arr[i]); i++; }
For loop, cached (inside for statement)
for (var i = 0, len = arr.length; i < len; i++) { someFn(arr[i]); }
For loop, cached (outside for statement)
var len = arr.length; for (var i = 0; i < len; i++) { someFn(arr[i]); }
For loop, i-- (caching inside for loop)
for (var i = arr.length; i > 0; i--) { someFn(arr[i]); }
For loop, i-- (caching outside for loop)
var i = arr.length; for (; i--;) { someFn(arr[i]); }
While loop, cached
var len = arr.length; var i = 0; while(i < len){ someFn(arr[i]); i++; }
While loop, i--
var i = arr.length; while(i--){ someFn(arr[i]); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
For loop, basic
While loop, basic
For loop, cached (inside for statement)
For loop, cached (outside for statement)
For loop, i-- (caching inside for loop)
For loop, i-- (caching outside for loop)
While loop, cached
While loop, i--

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 5 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/76.0.3809.100 Safari/537.36

Browser/OS: Chrome 76 on Windows

View result in a separate tab

Test name	Executions per second
For loop, basic	3264.0 Ops/sec
While loop, basic	3147.3 Ops/sec
For loop, cached (inside for statement)	5092.2 Ops/sec
For loop, cached (outside for statement)	5373.7 Ops/sec
For loop, i-- (caching inside for loop)	5192.6 Ops/sec
For loop, i-- (caching outside for loop)	5287.7 Ops/sec
While loop, cached	5155.0 Ops/sec
While loop, i--	5408.2 Ops/sec

Autogenerated LLM Summary (model llama3.2:3b, generated 2 months ago):

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks and explore what's being tested in this Loop Optimization benchmark.

**Benchmark Overview**

The Loop Optimization benchmark measures the performance differences between various for/while loops using the same function, `someFn`, which takes an index as input. The test cases are designed to demonstrate the impact of loop optimization techniques on execution speed.

**Loop Optimization Techniques**

The benchmark tests six different loop optimization approaches:

1. **For loop with cached array length**: `for (var i = 0, len = arr.length; i < len; i++) { someFn(arr[i]); }`
2. **For loop with cached array length and index increment inside the loop**: `for (var i = arr.length; i > 0; i--) { someFn(arr[i]); }`
3. **While loop with cached array length**: `var len = arr.length; while(i < len){someFn(arr[i]);i++;}`
4. **For loop, basic** without caching the array length or index increment: `for (var i = 0; i < arr.length; i++) { someFn(arr[i]); }`
5. **While loop, basic** without caching the array length or index increment: `var i = 0; while(i < arr.length){someFn(arr[i]);i++;}`
6. **For loop with cached array length and index decrement outside the loop**: `for (var i = 0; i < len; i--) { someFn(arr[i]); }`

**Pros and Cons of Each Approach**

Here's a brief analysis of each approach:

1. **Cached array length**: Reduces overhead by caching the array length once, but may lead to increased memory usage.
2. **Cached index increment inside the loop**: Can improve performance by reducing the number of increment operations, but may increase complexity and bug likelihood.
3. **While loop with cached array length**: Similar benefits as the for loop approach, but may have different performance characteristics due to the while loop's nature.
4. **Basic for loop**: Simplest implementation, but likely to be the slowest due to unnecessary overhead.
5. **Basic while loop**: Similar to the basic for loop, but with a different increment logic.
6. **For loop with cached index decrement outside the loop**: Combines the benefits of caching array length and index decrement reduction.

**Performance Results**

The benchmark results show that the optimized approaches outperform the basic versions, with the most significant performance gains achieved by using cached array lengths or index increments. The order of performance results is:

1. For loop with cached array length and index increment inside the loop
2. While loop with cached array length
3. For loop with cached array length
4. For loop with cached index decrement outside the loop
5. Basic for loop
6. Basic while loop

Keep in mind that these results are specific to this benchmark and may vary depending on other factors, such as hardware, software configurations, or JavaScript engine optimizations.

In conclusion, this Loop Optimization benchmark highlights the importance of optimizing loops in JavaScript code, particularly when it comes to caching array lengths or index increments. By applying simple yet effective techniques, developers can significantly improve the performance of their applications.

Related benchmarks:

Loop Optimization (version: 0)

Checking differences between various for/while loops.

Comparing performance of: For loop, basic vs While loop, basic vs For loop, cached (inside for statement) vs For loop, cached (outside for statement) vs For loop, i-- (caching inside for loop) vs For loop, i-- (caching outside for loop) vs While loop, cached vs While loop, i--

Created: 6 years ago by: Guest

Jump to the latest result

For loop, basic

While loop, basic

For loop, cached (inside for statement)

For loop, cached (outside for statement)

For loop, i-- (caching inside for loop)

For loop, i-- (caching outside for loop)

While loop, cached

While loop, i--

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 2 months ago):