What you’re about to see is a few benchmarks, all of them conducted on the browser-based JavaScript benchmark system SunSpider. Inside the post I’ll explain a bit better what SunSpider is for everyone who hasn’t seen it before, but what you need to know from here is that we’re testing both the stock browser and the newest version of Firefox (4) for Android. What you’re going to see is the T-Mobile G2x by LG, the HTC ThunderBolt running on Verizon’s LTE network, and the ATRIX 4G running on AT&T’s HSPA+ network.

What SunSpider does is sets up a group of JavaScript performance tasks which show how well your web browser handles real world tasks on your particular device. What that means essentially is it shows how well your device is going to use the internet inside a given browser on a daily basis. SunSpider is accepted by browser developers as an accurate test because it performs each of its tests multiple times and grabs what SunSpider claims is a 95% confidence interval. The lower the score you get, the better.

Here’s all the scores listed first, then the images all spread out:
ATRIX 4G
Stock: 4241.5ms
Firefox: 1842.2ms

HTC ThunderBolt
Stock: 5977.8ms
Firefox: 2685.9ms

LG G2x
Stock: 4414.9ms
Firefox: 1847.2ms

And just for fun, since it’s not final build, HTC Sensation
Stock: 4568.0ms

ATRIX 4G Stock

ATRIX 4G Firefox

ThunderBolt Stock

ThunderBolt Firefox

G2x Stock

G2x Firefox

HTC Sensation Stock [PRE-FINAL BUILD]