Ever since i started using Xubuntu I have noticed that whenever I run any heavy application like Eclipse, Tomcat Server or even when I open sites like facebook in multiple tabs in the Web Browser my system begins to lag. Even the mouse movement and Keyboard input are affected by it hence I am unable to open Virtual Console to close the application. The only way to get rid of it is to wait for 15 to 20 min or to reboot the system using REISUB. I tried using applications like Preload but even that didn't help.
I have not allocated any swap space but the memory usage of the system rarely crosses 2 GB. Even when the heavy applications were running, still more than 1 GB of the RAM was free. My laptop has 4 GB RAM and 2.13 GHz processor. Xubuntu version is 13.04 and i update my system regularly. Earlier i have used other distributions like OpenSuse but they all ran smoothly on my laptop. Even windows runs without any issue.
Is the swap space the problem or are there any logs i should check ? The dmesg and the kern.log don't show any abnormal behavior. Is there a way to change scheduling method which it uses or to lower priorities of applications so that they don't affect other applications ?