A high intensity discharge lamp, in certain embodiments, includes a uniquely shaped shoulder and dimensions selected to reduce stress and associated cracking. The uniquely shaped shoulder has a variable diameter, such as, e.g., a cup-shaped geometry, a curved funnel-shaped geometry, or a conical-shaped geometry. The selected or optimized dimensions may include a tip-to-neck distance, a tip-to-wall distance, and an internal diameter of the lamp. The selected or optimized dimensions also may include a uniform wall thickness, an arc gap distance, and an electrode thickness. These dimensions and shapes are selected to reduce undesirably high maximum stresses and temperatures in the lamp. As a result, the lamp is able to provide higher performance with a longer life due to a decreased risk of stress cracking during rapid start up and steady state operation.