Lol don’t know where that was implied but sure

The majority of the cost in applying the death penalty isn't the method of execution, it's all the administrative/court work to make sure you aren't executing someone who shouldn't be, which still allows innocent people on death row at an estimated rate of 4%.

It's expensive because the pre-trial preparations are more extensive, the trial is longer, death row is more expensive to run and staff, and they get a lot of chances to appeal up to the last minute. Not a lot of the cost comes from the execution method itself.

Which of those things would you like to cut for efficiency? Should we not spend as much on the trials? Make them shorter and speed things up? Should we reduce security on death row? Should we not give them as many chances to appeal?

The only way to make it cheaper is to make it even crueler. Those decades of suffering might end with a pardon, or a acquittal, or a new trial that leads to a reduced sentence. There's a reason it takes so long.