Online installer downloads entire package for each small change

As one of the masses that does not have a lightning speed Internet connection, and no access to one, the online installer takes many hours (days) to download just the basic Qt package and regularly comes up with connection dropped errors during this process, stopping it until it gets input so it can't even be left to get on with it.

The bug

As if the above isn't bad enough, this is made infinitely worse by the fact that when even the smallest change is needed the installer downloads every single file again instead of caching those you downloaded previously and reusing them.

Solution

Instead of placing the downloaded installer files in the %temp% folder and then deleting them, cache them in the install folder and reuse them when required. Or just make the offline installer available again instead of penalising the open source users.