As part of a new Gamasutra feature , developers discuss the challenges and opportunities HTML5 creates -- and performance issues are "a big, big problem" according to EA's Richard Hilleman.While HTML5 might be designed to run on a wide range of devices, there's still no reliable way to maintain performance across varying hardware specifications.EA creative director Richard Hilleman recently shared his frustrations with the platform at the San Francisco-based New Game Conference, noting that his team's experimental 3D animations ran great on a MacBook Air, but chugged on more powerful hardware."On my own computer, which runs on an i7, I couldn't get more than a few frames per second [from our demo], Hilleman said. He explained that "high performance JavaScript is obtuse at best," so it's hard to predict how an app will run on a given hardware specification."I don't know how to explain that to a customer. That's a big, big problem," he added.Mobile-focused HTML5 developers are particularly susceptible to these problems, as their games need to run on a wide array of smartphones and other mobile devices.Stewart Putney, an experienced HTML5 developer and former CEO of the recently shuttered Moblyng, told Gamasutra that his company would test its games on literally dozens of devices. "For iOS it is simple: 3GS, 4, 4S, iPad, iPad2. Android is much more fragmented; each handset manufacturer tends to make small -- mostly undocumented -- changes to the browser on their devices. For native Android apps, this is no big deal. For HTML5 apps, it can mean apps simply don't work," he said."To get good quality, our apps must be tested on a range of popular devices -- it is the only way to be sure apps are working properly. I believe we will see more testing tools and better standards moving forward -- but Android QA is a real pain point for HTML5 development," he continued.The full feature, which features six more relevant issues with HTML5 which developers should take note of before embarking on projects, is live now on Gamasutra