Gas Range slow to get to 500 degrees

This is a gas stove, the burners heat fine.
Oven takes 16 minutes to reach 350,
Oven takes 36 minutes to reach 475 and
Oven takes 45 minutes to reach 500.

The stove never used to take this long to reach 500.

It appears both burners on the bottom are working.

Any suggestions would be appreciated.

Thanks!