PCB is lagging while selecting and moving the components

Hi Hemanth, there could a few things to test and try. 

Firstly, the obvious stuff - please verify the system meets the minimum hardware requirements. These are contained in the Installation guide in the installer or hotfix download, typically "pcbInstall.pdf".  Also confirm full permissions to the installation disk and investigate any potential network policies or firewall issues affecting WAN performance.

For the pcb database optimization:

Run the Performance Advisor under Tools -> Database Check and clear any errors or issues detected.
Follow recommendations for dealing with large designs: check Canvas oversize in the Design Parameters (Extents). Purge all unused subclasses possibly imported from idx or other. 

Disable any unnecessary Constraints using Analysis Modes. Turn off any checks you are not using or that have empty constraint values inside. 
To reset any hindering Editor preference setting, you can try renaming the pcbenv folder stored in your %home/% directory. Restarting Allegro PCB Editor will create a new fresh folder with default settings. .
Run the tool in administrator mode. 

Let me know if any of this helps!