Computer is slowing down

[John R. Sowden]

I have been using the same computer (Pentium 4 3.0GHz 1GB RAM (shared 
875 MB for non-video use) 1.5GB swap, 13.10 xubuntu/xfce desktop) for 
several years, and its been working fine.  Click on an icon, the program 
executes right away, etc.

In the last year, the system seems to have been slowing down.  It takes 
2-3 seconds from a click on an icon until the program starts to execute 
(not up and running).  I am wondering if xubuntu is getting  bigger and 
bigger, taking more ram (I assume that is the issue) without letting us 
know that requirements are changing.  I also am wondering if more 
non-essential programs are being added to the install that are running 
in ram, that are not necessarily needed.

Any thoughts?

John