Swift: slow build times when changing struct code - swift

Question

tl;dr
Applying a code change to a commonly used struct causes very slow build times. Can this be avoided?
I have a rather large Swift project (Xcode 9.2) where I use a struct to hold all styling information (colors, spacings, etc.) used by in the app, something like:
struct Style {
var iconColor: UIColor = .darkGray
var lightTextColor: UIColor = .gray
// ... and many more properties ...
static var defaultStyle: Style {
return Style()
}
static var fancyStyle: Style {
var style = Style()
// ... override style props for more fancyness ...
return style
}
}
Every view controller (there are about 30 VCs in the project, all created in code -- no storyboards used) has a Style instance and uses it when rendering its UI:
class MyViewController: UIViewController {
var style = Style.defaultStyle // can be overridden by creator of the VC
override func viewDidLoad() {
super.viewDidLoad()
myLabel.textColor = style.lightTextColor
}
}
This works pretty nicely and allows to change settings in one place only, without polluting the namespace with global constants.
However, I noticed that when changing a property's default value inside the struct the compile time rises dramatically, Xcode basically performs a full rebuild. E.g. changing the above definition of Style.lightTextColor to var lightTextColor: UIColor = .green leads to a build time comparable to a full rebuild of the project. If, however, I change the value directly where it is used; e.g. in the view controller: myLabel.textColor = .green, the project builds very quickly.
Is there a solution for this, preferably by configuring the compiler to do ... less work in this case?