In the dfm(the UI declaration file) the positions of elements are always absolute with relation to the forms top left point, they are just recalculated on the fly when a change in the form causes them to resize. Using alignment is great but it doesn't solve the problem. Not really that big of an issue in the big picture, just makes diffing forms annoying.
Don't use delphi, the rad sucks for everything but dragging and dropping components. The drag and drop is also a pain in the ass because it will constantly adjust the layout, making every commit be filled with noise.
Maybe all frontend is this bad though, I don't have much experience with other tools.
Well it really depends on what operations you expect to be instant. Basic editing like movement, inserting, etc is instant, but summing from 1 to 100000000000000000000000 is where elisp would show its poor performance.