LinuxTent

According to the email from then wolfram support, there is a patched shared libraries for the new linux kernels. Apparently, Mathematica having problems running on 2.6.28+. I followed the email of the technical support and it worked for me and the cpu usage dropped from 80%+ on average to less than 5% !!!

The solution as mention in ubuntu forums [1]

1. Download the file here:

   http://download.wolfram.com/?key=61JJHE

2. Place the shared library in
   /usr/local/Wolfram/Mathematica/7.0/SystemFiles/Libraries/Linux
3. Download these files:

   http://download.wolfram.com/?key=MK4ZR8
   http://download.wolfram.com/?key=YHDAH4

4. Place them in
   /usr/local/Wolfram/Mathematica/7.0/SystemFiles/Libraries/Linux-x86-64

Good Luck