John Moses designed it with the 5 in slide. The balance he came up with has been working for 106 years.Its not done yet.
In the first part of recoil,till unlocking,the slide and barrel area team.They weigh in together.
Well,the Commander is a little lighter in the slide.The Officers,lighter still.Then the Defender or whatever other pug nosed 1911's have been made.
Its an amazing testimony to JMB's design that it is so flexible and forgiving.
I have been told that for long term reliability the 5 in Gov't is best,and as slides get shorter reliability goes down.I can't say for sure,I stopped at the Commander length.
Speed competition looks for hundtredths of a second.Gain 1/100th of a second each slide cycle,you have something. A little less inertia bounce from the slide going to battery makes for control. These guys lighten slides.
But,they have full length or commander lengt slides.They have comps both slowing the slide via gas,and adding weight.Or they have bull barrels.
So I suggest you consider the gas assist at slowing the slide,plus more steel in the longer slides,before you reduce the weight of your short slide.
A lightened 5 in slide will still probably weigh more than a Defender slide.