For a 2 lb roast in a slow cooker, the typical cooking time is about 8 to 10 hours on Low heat or 4 to 6 hours on High heat. Cooking it on Low heat for around 8 to 10 hours is recommended for the most tender and juicy results. The exact time can vary depending on the size and type of roast, but this range is a standard guideline until the meat is fork tender.