edit: JavaScript was born in 1995. Still, on the JavaScript VM scene three months is a lifetime. As Mark Rowe commented, in this post I benchmarked a nightly V8 against a three months old JavaScriptCore (SquirrelFish). Which turned out to be unfair. Check out the numbers in the newer "V8 and JavaScriptCore are really, really fast" post instead.
Short version
On my machine given my unscientific measurements in Q2 2009:V8 is really, really fast.SquirrelFish is really fast, and often close to really, really fast.TraceMonkey is fast, but often far behind really fast.Longer version
If you haven't been living under a rock the last year then you know that there has been substantial progress in the JavaScript VM camps. I wanted to get some performance numbers from recent versions of V8, TraceMonkey and SquirrelFish.
Here's what I used (I'm on Mac OS X). It was the most recent versions at the time of writing (May 22nd 2009).
V8: Chromium 3.0.182 (182.0)
TraceMonkey: Firefox 3.5b4
SquirrelFish (extreme): Safari 4 Public Beta (5528.17)
To get somewhat fair performance figures I ran three benchmark suites: Dromaeo, V8 Benchmark Suite and SunSpider. I ran the JavaScript Tests part of Dromaeo since I intended to measure JavaScript, not DOM, performance.
Here are the very unscientific results from my Core 2 Duo laptop. I re-ran some of the tests a few times, best result posted. The browser was restarted between each test run.
For the SunSpider bars lower is better, for the others higher is better. I may update this blog post with new numbers if I get better results (with the same versions). V8 is the fastest, SquirrelFish is second and TraceMonkey comes in last in all benchmarks.
edit: These numbers are unfair since V8 was a nightly build (no stable Chrome released yet for Mac OS X) while the others were a few months old. Check out the less unfair numbers in the newer "V8 and JavaScriptCore are really, really fast" post instead.
All VM's have their own merits. Nothing beats getting real-world performance characteristics by throwing your own programs at them so do that if you want to do a serious evaluation of them. You may also be interested in evaluating code size and memory consumption, especially if you're into embedding. Oh and in that case, make sure that the JIT has a backend for your target.
To me the V8 source code was the most beautiful and TraceMonkey the least. This is very subjective so take a look for yourself. And while you're checking out the code run the log command so that you get a feeling of how fast the project is moving. And what they're changing. That may be a good or bad thing to you.
If you just want to run a fast browser then all three should be plenty fast for most (current) use cases. I run Mozilla Firefox myself since I'm addicted to extensions such as LastPass and Tree Style Tab.
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