We love it when performance and portability come together. Twinhead’s new N23PB is a 4.7-pound laptop with a footprint of just 11.1 x 9.6 inches and 1.1 inches thick. Encased in a sleek shell, the N23PB is one smooth-looking laptop.

Belying that very portable frame, the N23PB offers very nice performance, which is borne out by the system’s outstanding MobileMark performance rating of 214. This expert balance of performance and portability is the result of the N23PB’s installed 1.7-GHz Intel Pentium M processor. Although this CPU is extremely efficient, it manages to offer roughly the same performance as a Pentium 4 running a full gigahertz faster.

With two megabytes of L2 cache fitted into the processor’s core and half a gigabyte of DDR SDRAM mounted on the motherboard, the Pentium M processor in the N23PB didn’t have any trouble handling large spreadsheets in Excel, manipulating digital images in Photoshop, or performing any other task.

A big reason for the Twinhead’s prowess is its speedy hard drive. While most ultraportable notebooks have just a 4,200-rpm hard drive, the Twinhead N23PB boasts a desktop-class 7,200-rpm hard drive, complete with a large 8MB cache memory buffer to accelerate the flow of data between the drive and system RAM. This fast drive really helps in applications like Photoshop that need to frequently write and read large amounts of data to and from the hard disk.

Intel’s i855 video adapter in the system uses a portion of the system’s main memory, but we didn’t experience any trouble running two or more applications at the same time. We encoded an MP3 and edited a digital photo at the same time fairly easily.

Not having dedicated graphics does bring down the N23PB’s gaming performance. Still, while the Twinhead renders graphics in 3D games with a bit of blockiness and choppiness, the effect isn’t nearly as disastrous as we’ve seen with other laptops that have integrated video. Likewise, the system’s 12.1-inch display isn’t ideal for gaming, but this XGA screen is bright and crisp and plays DVD movies without any ghosting, pixelation, or artifacts.

Unfortunately, you won’t be editing much video, as the N23PB doesn’t offer a FireWire port. On the upside, it features three USB 2.0 ports, in addition to VGA, headphone, and microphone jacks. For networking and connecting to the Internet, there’s an Intel PRO/Wireless 2200BG Wi-Fi adapter.

While plenty fast, the performance of the wireless radio surprised us by cutting a whopping 41 minutes off the system’s battery runtime when activated. Fortunately, the system has two features that pick up the slack for this shortcoming. First, the N23PB offers a hardwired Wi-Fi power button right above the keyboard. Second, this system has battery life to spare, offering a remarkable 4 hours and 18 minutes of battery runtime with the Wi-Fi adapter disabled.

Considering its comfortable full-sized keyboard, smooth touchpad with a scroll button, combination DVD-ROM/CD-RW drive, and a Memory Stick/MultiMediaCard/Secure Digital card reader, you can see that the Twinhead N23PB packs not only plenty of performance, but also a number of nice features into its compact frame.

As long as you choose to upgrade beyond the standard 1-year warranty, the Twinhead N23PB will serve you well. We just wish users didn’t have to complete a long registration form online just to configure their notebook.