Why is my gas stove taking 30+ seconds to light?
The problem is clearly with the gas feed.  If other portions (like other burners) work okay, the plumbing in common to those and further upstream is all fine.  The problem would be the last portions to the burners.

I would start by removing the grate, lifting off the burner caps, and lift up the burner assemblies.  Any foreign matter in there?  If there is goo, run them through the dishwasher, toothpaste and an old toothbrush, or a steel wool cleaning pad and water to get it off.

Have a look at the igniter tips:  are they clean and shiny?  Do the heavily used tips look similar to the lightly used tips?  200&ndash;400 grit sandpaper is the easy fix for these.  Place the burners back into position carefully, making sure each seats securely and aligns with the igniter.  Place the caps back on paying attention to the alignment of the nub-like posts underneath (which keeps them from sliding off) so they don't cause a gap by making the cap sit up on a post.

If that doesn't renew performance, it is either a valve or plumbing problem.  I would call an appliance repairman at that point for his/her knowledge of the exact problems with that model as well as the range of solutions and prices.