Google has done a good job of improving its Chrome OS software. But the flagship Chromebook doesn’t fulfill the software’s potential.

Chrome OS is a PC operating system that competes with Microsoft’s Windows and Apple’s OS X. It’s based on Linux and built around Google’s Chrome browser. Everything you do on a Chromebook — the moniker given to laptops running Chrome OS — is done through the Chrome browser, including sending email, changing settings and playing games.

I’ve been testing the Samsung Chromebook, which is the first Chrome computer to feature a chip based on technology from ARM, rather than an Intel processor. Thanks in part to that change, the new Chromebook is cheaper, lighter and thinner, and its battery lasts longer than its predecessors.

Those are all good things, but I found the new Chromebook to be a disappointing device. It performs OK if all you want to do is view a Web page or two. But if you try to use it like a regular office PC, with multiple applications or browser windows running at once, it’s sluggish and frustrating.

The Chromebook is unremarkable in its appearance. Its silver-colored plastic shell is thin, but not as slim as the new Windows-based ultrabooks. And it’s lightweight; at less than 2½ pounds, it’s almost as light as Apple’s featherweight MacBook Air.

What sets it apart is its operating system.

When Google launched Chrome OS more than two years ago, it was buggy, lacked many features and sported a radical new interface that included neither windowed applications nor a traditional desktop. But Google has updated the software repeatedly since then, making it much more reliable and satisfying to use. Because it’s simpler than a traditional operating system, Chrome starts up, shuts down and resumes from sleep quickly.

Chromebooks don’t run traditional programs and don’t have access to many popular PC apps, such as Apple’s iTunes or Microsoft Office. Instead, they run Web-based applications, which number in the thousands and can in many cases replace traditional PC programs. You can’t yet run many sophisticated PC games, but you can edit photos, write letters and even design 3-D objects in a browser window.

The other big distinction of the new Chromebook is its Samsung-built ARM chip. ARM processors, which are known for being extremely power-efficient, dominate the world of smartphones and tablets, but are just starting to show up in PCs.

Google says the new Chromebook should run for more than 6 hours on a single charge and that’s about what I experienced. ARM chips can also run without fans, which makes the Chromebook exceptionally quiet.

But I found the new Chromebook to be underpowered. Just going through my Gmail inbox seemed to tax the device.

And when I tried to do my regular work on it, the Chromebook felt even more inadequate. I frequently have a dozen or more browser tabs open, displaying my inbox, my Facebook news feed, my Twitter stream, my calendar, articles I’ve looked up in my research, and more.

My office laptop balances all these tabs well enough. I can usually flip from tab to tab quickly. And I can easily see if I’ve gotten new email or instant messages.

The Chromebook, by contrast, struggled to keep up with even half the tabs I typically have open.