In our first quarter mobile analysis we were surprised to see that, rather than scaling back after fourth-quarter 2014 ? the data-heavy holiday shopping season ? retail sites actually increased the size of their mobile homepages by nearly 10 percent in the subsequent quarter. 

That trend continued in the second quarter, as the average retail mobile homepage continued to grow in total bytes, this time by an average of 10.4 percent. 

Not surprisingly, this resulted in another slowdown of those homepages, with average webpage load times rising 13.6 percent from 2.13 seconds in the first quarter, to 2.42 in the second quarter. 

Given that a page will load slower if heavier, it is not a good sign that mobile retail sites as a whole are adding to their page size. 

What is worse is that the performance impact of these added elements is clearly not being mitigated by page speed optimization techniques.

Getting to the good news, we have a new winner atop the page speed rankings this quarter, as Grainger moves up from fourth to first thanks to the most lightweight mobile homepage of all the retail sites we tested, as well as the fewest objects on the page. 

Meanwhile, the second-fastest site, Walmart, was actually in the lower half as far as page size and objects are concerned, showing what a difference speed optimization techniques can make when properly implemented.

Additionally, in light of the Mobilegeddon guidelines that went into effect in May, we looked at the number of sites that redirect to separate mobile page. 

In the retail category, more than half of the sites ? 16 out of 30 ? redirect to a specific mobile URL, while the rest have optimized their homepage for mobile browsing.

Top performers (webpage load time):

1. Grainger

2. Walmart

3. Gap

4. Costco

5. Amazon

Despite a slight drop in the average mobile homepage performance from the first quarter ? 1.7 percent slower ? the banking sector was still markedly better than the retail industry for the second straight quarter, registering an average mobile homepage load time of 2.03 seconds. 

The size of the average banking homepage also dropped by 13.3 percent, which is interesting when contrasted with the slightly slower load times, indicating that third-party services and elements may have negatively impacted the sites this time around.

For the fourth straight quarter, Citizens Bank led the way with the fastest mobile homepage. Its blueprint has become one for other banks to follow. 

While Citizens Bank does not have the lightest page ? three others were lighter ? it has no third-party services or elements on the homepage, and just nine total objects. This is not only valuable from a performance standpoint, as it eliminates many potential single points of failure, but also helps put customers minds? at ease. 

When browsing a site that handles sensitive information such as personal finances, customers will be reassured knowing that there are no third-party services on the page which could potentially compromise private information.

Four of the 10 banking sites also redirect to a separate mobile URL.

Top performers:

1. Citizens Bank

2. US Bank

3. Wells Fargo

4. Chase

5. Citibank

For the first time in the past year, the travel site index beat out the retail sites in average mobile homepage speed, despite the fact that they have gotten slightly slower since first quarter. 

The average mobile travel site was 2.33 seconds this quarter, a 4.4 percent increase from the previous mark of 2.23. 

Once again, however, that average time was dragged down by the performance of one airline that came in at a whopping 5.50 seconds, with the next slowest page registering a mobile homepage load time of 4.22 seconds.

Much of the top five remains unchanged from the previous quarter, with Google Flights continuing its perpetual dominance as the only mobile site to come in under one second, coupled with yet another quarter of perfect 100 percent availability. 

TripAdvisor?s data-heavy homepage is nonetheless one of the fastest and most reliable thanks to a relatively small number of third-party services and objects on the page, while Kayak is once again among the fastest as well.

One of the big standouts this time around is Priceline, which rebounded from a rough first quarter to have the second-fastest mobile site in the industry. 

Much of Priceline?s rebound can be attributed to a slimmed-down homepage that is less than a third of the size of last quarter?s. This helped shave over two full seconds off of its median mobile homepage load time. 

That type of improvement validates a big effort on the part of Priceline?s IT team to speed up its mobile site.

Less than half ? nine out of 22 ? of the travel sites are still using a separate mobile URL, while the rest are using optimized mobile site design.

Top performers:

1. Google Flights

2. Priceline

3. Kayak

4. Southwest

5. TripAdvisor

WHILE THIRD-PARTY services and elements such as ads and tracking tags may be necessary to drive revenues and gain valuable insight into end-user experience and behavior, their presence on a page will always add to the overall page size and present a potential pitfall in terms of performance. 

By limiting these elements and deploying optimization techniques for those that must be there, site administrators can greatly reduce any negative impact on the end user experience. 

Every third party service or element on a site ? particularly a mobile site ? must be vetted and evaluated to determine if its presence is going to have a net positive or negative effect on conversions and the company?s bottom line. 

Additionally, site administrators should protect themselves with service level agreements to hold their external service providers accountable and ensure compensation for any third- party failures that affect the site?s overall performance.