Hi Samid,
Please check the below URL for the performance tuning:
http://darrylgriffiths.blogspot.in/2011/08/basic-performance-tuning-guide-sap.html
ABAP Performance and Tuning - ABAP Development - SCN Wiki
SAP R/3 Performance Monitoring and Tuning
http://scn.sap.com/docs/DOC-47062
http://soumen.wordpress.com/performance-tuning-of-sap-another-experiance/st04-a-magic-tcode-for-
Regards,
Rishi