Mobile travel and hospitality sites slowed slightly in October by 0.87 seconds, according Keynote Systems’ Mobile Travel and Hospitality Index.

Out of 30 sites, only two sites had more than one second page load time improvement. United improved by 1.8 seconds and Marriott improved by 2.58 seconds. Fully 25 out of 30 sites had a slower average page load time compared to the month of September. Thrifty car rentals dropped 2.01 seconds and Vegas.com page load times increased by 4.92 seconds, the largest performance drop for the month.

On the other hand, the average index reliability increased slightly by 0.06 percentage points from a mix of results across the index. Reliability of five out of 30 sites was three percentage points higher. Avis increased reliability by 11.91 percentage points and Kayak increased 9.28 percentage points. Six sites dropped more than three percentage points, including Southwest Airlines, Travelocity, US Airways, United, Vegas.com and Visit Orlando.

Fairmont continued to have the fastest page load time, but dropped in reliability in October. AirTran claimed the second fastest page load time at 5.42 seconds and had the highest reliability of 98.86 percent.

So why such a drop in performance of Vegas.com’s mobile site? Keynote says Vegas.com rolled out a new mobile page in mid-October. The change resulted in BlackBerry Curve users no longer being redirected to the mobile site but instead receiving the full website. As a result, the average page load time became slower by 4.92 seconds and reliability dropped by 5.97 percentage points.

“Redirects are the most often overlooked function for a well-designed mobile website,” said Herman Ng, mobile performance evangelist at Keynote Systems, in a statement. “Ensuring that a well-designed mobile site is returned is the very first step in giving mobile users a good experience.”

Other than Vegas.com, Kayak also did not redirect BlackBerry Curve users to their mobile site, and MGM Grand returned their full web page for users using HTC EVO (an Android OS device).

In October, Keynote also looked at mobile sites returned for iPhone 4 in terms of the number of domains and number of page objects. It is no surprise that sites with a small number of domains and small number of page objects were generally faster, such as Fairmont’s mobile site with two domains and seven objects for their iPhone mobile site.

Visit Orlando, with 11 domains and an average of 36 page objects, had the slowest page load time of 22.52 seconds. However, not all sites with a higher number of domains or page objects had slowest page load times. For instance, Holiday Inn had an average of 10 domains and 37 page objects and a medium range page load time of 14.85 seconds.

Keynote repeatedly tests the sites in the index hourly and around the clock from four locations over the leading four U.S. wireless networks emulating the browsers of four different devices: the iPhone 4 on AT&T, the HTC EVO (Android on Sprint), the Motorola Droid X (Android on Verizon Wireless) and the BlackBerry Curve on T-Mobile. Data is collected from: San Francisco, New York, Dallas and Chicago and then aggregated to provide an overall monthly average in terms of both speed and reliability.