How to speed up the Linux System

[chandrachud nanduri <nmchandrachud yahoo co in>]

Hi Guys , 
             Off late , I have noticed that  my system has become very slow . I have GNOME desktop environment as my default environment .
I do not have many services on . Any application , as small as a Konsole takes ages to open . The Office Applications takes centuries to open .
How do I make my system speed up . Do I have to reinstall ? 
Also , my friends say that GNOME is much slower than KDE . Is this true ? Should I change to KDE ???
Thanks in Advance ,
N.M.Chandrachud

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