So far everything has gone well; we have made the page load faster while decreasing the load on the server, but...
What Can Be Done?
While the current Magento merging system is flawed, it would only take a minor adjustment to fix this critical issue.
<default> <reference name="head"> <action method="addJs"><script>prototype/prototype.js</script><group>global</group></action> <action method="addJs"><script>scriptaculous/builder.js</script><group>global</group></action> <action method="addJs"><script>scriptaculous/effects.js</script><group>global</group></action> <action method="addJs"><script>varien/form.js</script><group>global</group></action> </reference> </default> <catalog_product_view> <reference name="head"> <action method="addJs"><script>varien/product.js</script><group>product</group></action> <action method="addJs"><script>varien/configurable.js</script><group>product</group></action> </reference> </catalog_product_view>
Update: Although Magento still hasn't implemented this feature (maybe in v2?), you can offset this problem a little by minifying your JS and CSS. To make this easy, we have developed the Magento extension Opti. For truly fast speeds, use this with our Magento Full Page Cache extension!