Have you ever try to install a new package, using Kali aptitude manage.
You might noticed that the speed you are getting in Kali is very less as compared to the actual speed which you might get in IDM etc
By default, Kali source list uses HTTP protocol. Just change it to HTTPS
Also, install a package using this command (just 149kb package)
apt-get install apt-transport-https
This package will set a redirection policy to HTTPS
Note: only change the protocol not the subdomain.
Source list path: /etc/apt/sources.list
Source list example:
deb https://http.kali.org/kali kali-rolling main contrib non-free deb-src https://http.kali.org/kali kali-rolling main contrib non-free
Also please note that, 1st install package,
And then edit source list