What's the deal here? I've got one of those glass Vision oval roasters which I occasionally use for braising when the roast won't fit my Dutch Oven. Using time and temp for a Dutch Oven, this glass thang cooks the roast in half the time, defeating the whole purpose of slow cooking. But once cooked that fast, even the toughest roasts, chuck and round, are fork-tender, maybe a little over-done, but good. So is there a formula for reducing the temp when braising in glass?