To Restore default setting :

Open your terminal and use the following command
~$ dconf reset -f /

To speed up your system :

• Autoremove will remove unnecessary crabs remained while uninstalling apps .

  ~$ sudo apt autoremove

• Autoclean will remove caches .

  ~$ sudo apt autoclean

Remove Startup application :

When you start you pc startup apllication makes a bit slower while opening.

So we can remove this by going to the /.config directory :

~$ cd ~/.config

~$ cd autostart

Either remove filese with .desktop extension or move somewhere if you want backup

For removing :

~$ rm *.deskotp

Change GRUB_TIMEOUT 10 to 3

Goto the following directory :

~$ sudo gedit /etc/default/grub

change GRUB_TIMEOUT to 3

and save the file .
And you are done , enjoy fast development experience on your linux machine .