Performance Testing:-testing the present wroking condition 
of the product

Regression Testing:-Regression Testing is checking for the 
newly added functionality causing any erros interms of 
functionality and the common functionality should be stable 
in the latest and the previous versions

Performance Testing
     Testing the application  how speed is is working
Estimation of response time of server/CPU.
Perfromence of the application depends on the technology 
used to built the software.
The network capability(BandWidth).
Server capacity to handle the max. number of requests per a 
time.
Performance testing is divided into three tests again
1.Load Testing
2.Stress Testing
3.Volume Testing
Perfromance testing is very important  in WebApplications
,E-Commerce applications,Online banking applications..etc.

Regression Testing:-Regression Testing is checking for the 
newly added  or defect fixed functionality causing any 
erros interms of functionality and the common functionality 
should be stable in the latest and the previous versions

  If you still have any doubt feel free to mail me at :  
rajendra_penumalli@yahoo.com
or call me:9885162742

performance testing is done to check for real time impact of
load, stress & volume on the application, when all the
modules are ready and is working as an complete application. 

Regression testing is done to check for the impact of the
fixed bug, new added features either on single module or all
the module. this is done till alpha testing.