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

Performance Testing
     Testing the application  how speed is is working
Estimation of response time of server/CPU.

Performance 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

Performance testing is very important  in web applications
,E-Commerce applications,Online banking applications..etc.
Regression Testing:-Regression Testing is checking for the 
newly added  or defect fixed functionality causing any 
errors in terms of functionality and the common functionality 
should be stable in the latest and the previous versions

performance Testing manually for web site can be done By noting the time to load  page or perform any action with 
stop watch. I know it sounds funny but this is the way 
performance is tested manually.

Timing for both read and update transactions should be
gathered to determine whether system functions are being
performed in an acceptable time frame. This should be done
standalone and then in a multi user environment to determine
the effect of multiple transactions on the timing of a
single transaction.

parameters to consider for Performance Testing

Response Time during data retrieval ,calculations, 
turn around time, Bandwidth, Web Page load time during 
Multiple user logins,capacity,volume,load,
The time parameters for performance testing are Elapsed 
time , response time , hits/second and throughputs.

generally we consider five parameters for Performance Testing
 Response time
 page download time
Through put 
transactions per second
Turn around time

Performance: Performance testing of an application for the 
fixed time and fixed number of the user.

to do the performance testing Manualy

We can test it manually but we don't get accurate result.
We don't have separate test cases.
exactly we will do it with tool i.e Load runner,Act,Web load

Performance testing means checking the application whether 
it is working upto the level of the user expectations, i.e. 
acceptance of no. of requests at a given time, responce 
time, number of users at a time, etc.

Testers will verify how fast our application responds to 
the users request.

how much load is applyed on server/cpu for executing 
current application and also finding the responce time for 
every request

how much load is applyed on server/cpu for executing 
current application and also finding the responce time for 
every request

performence testing - to test the performence of the 
application under load. 
It determines speed, scalability, stability,confidence
.....while focusing on 
            ->user expectation
            ->system consideration
            _>costs
    Specifically,it answers
           How many.....?
           How much....?
           what happens....?