• by Steve Smith  @popeyesm, December 21, 2011

A month after its release, and in the face of early criticism of Amazon’s first entry into the tablet market, the e-retailer released a Kindle Fire operating system update designed to address consumer concerns. Overnight, Kindle Fire units started updating themselves with version 6.2.1 of the underlying operating system, designed to improve overall performance and help solve parental control concerns.

A Restrictions option now lets the owner of the tablet apply a password to the WiFi connection. The feature is a response to reports from parents that children can too easily buy new content at the press of a button. Amazon uses its patented One-Click ordering mechanism in the Kindle Fire, which provides seamless ordering without a series of confirmation screens.

But parents have reported that once the unit is in their kids’ hands, they can easily pile up book and video purchases without constraint. The new WiFi password does block a new user from accessing the network automatically with the device, but once WiFi connections are established, the user is free to order with a single click.

Amazon has also modified options for the Home screen, which is dominated by a pile of icons representing recently accessed content. The update does not give the option to turn this feature off, but it does allow the user to remove an icon from the stack.

Amazon says in its update notes that the new software “enhances fluidity and performance” and improves touch navigation. Early reviews of the Kindle Fire note jagged interface performance and noticeable lag in the unit’s touch response.

In our subjective tests of the update, the new software does seem to improve on-screen navigation of icons and page flipping, which had been halting in the original version of the operating system. Some reviewers have also taken issue with Amazon’s claims that its browser experience is accelerated by a cloud-based “Silk” technology.

We detected in this update faster page drawing and data retrieval in some Web pages. Touch responsiveness itself remained uneven: stronger in the top-level interface elements and page flipping, still lagging when scrolling pages with many elements or in digital magazines.

Despite mixed reviews, Amazon’s inexpensive ($199) Kindle Fire is lighting up the market and the expectations of many analysts. Amazon itself is claiming to be selling 1 million units a week in the entire Kindle line, which includes the lower-priced e-ink based reader devices.

The company will not break out specific sales for the Fire tablet, but insists it is their fastest-selling product. Several analysts have predicted that Amazon will sell between 3.5 and 5 million units this holiday shopping season.