Diagnosis
No. A slow preheat points to a failing bake element or a weak connection. The bake element is the lower heating coil.
How to Fix It
Visually inspect the bake element at the oven floor. Look for any blistering, cracks, or sections that don't glow red when the oven is on bake. A damaged element must be replaced. Part is typically a 240V, 2600W tubular heating element.
If That Didn't Work
The issue could be the oven temperature sensor. Its resistance value drifts. You need a multimeter to test it. Unplug the range, locate the sensor at the top rear of the oven cavity, disconnect it, and check resistance. At room temp (70°F), it should read about 1080-1090 ohms.
Heads Up
Never operate an oven with a visibly damaged heating element. It can arc and short. Disconnect power before inspecting any internal components.