You don't need to click the Save button; clicking + has already saved the static lease. The Save button is for any changes in the top section (range, lease time etc)
The settings page doesn't use an ajax call.
This form is sent using a normal POST.
The page goes to the top because the whole page is reloaded.
Edit:
I think it's possible to use a different alert type, with a simple modification.
The page will still reload, but will be a "floating" alert, not requiring to scroll the page to read it.
My initial idea is to use a floating alert, on the top right. No need to scroll, like this example:
This is just a test showing the desired result, but I'm not sure if this is possible without rewriting all other functions that return alerts/messages on this page.
Please be aware: there's no planned release date (in fact, there's no guarantee this will ever be released).
This would be better for sure, same as how the API tab has strategically located Save buttons. It caught me out a few weeks back in a slightly different way. I'd added an entry, made some tweaks and hit save and left the page, only for it not to be working, and found that my entry wasn't even present. I ended up discovering that Save button didn't save my entry and that the + icons do that separately.