nobody wrote:

We have a GE glass cooktop with 4 natural gas burners in our
home. The cooktop has an electric spark igniter. Over the
past year, we have noticed that the burners are taking
longer and longer for gas to reach them and be ignited by
the spark. Turning on several burners initially helps some.
There has never been the odor of gas, by the way, just a
progressive delay in the gas reaching the igniter.

What is the problem and how can it be solved?

Sounds like orifice(s) in supply line getting plugged and reducing
flow...