Found the solution for this problem
When .NET redistributable is installed, it compiles the high priority assemblies in 5 to 10 minutes and then waits until your computer is idle to process the low priority assemblies. The following method forces all of the remaining items to be compiled with a command called NGEN.exe. Follow these steps:
1) Run cmd.exe from Start > Run
2) Type cd\
3) Type cd Windows\Microsoft.NET\Framework\v2.0.50727
4) Type NGEN executequeueditems and press Enter
5) It will take about 1-10minutes depending upon system speed. After the process is complete, the following prompt will appear in the command prompt
C:\Windows\Microsoft.NET\Framework\v2.0.50727>
6) Type exit to close the command prompt.
After performing these steps, your computer will boot up at usual speed.