Selenium performance with .NET and Jenkins - How to profile and improve it? - asp.net

Question

I have an ASP.NET website that I want to test with Selenium. I want to setup a Jenkins instance on a "staging" virtual machine, to run the tests automatically.
The problem is that the tests run very slowly - several times slower than on my development machine. A single, simple test can take more than 2-3 minutes.
I'd like to know if this is to be expected, if there are any obvious pitfalls for such a testing setup as mine, and if there's anything I can do to profile and improve the performance of the test suite.
Info:
Tests run on a 2.7GHz 2GB Ram virtual machine with Windows 7 64bit.
My dev machine is similar, but with a 32-bit Win installation.
The following is done by Jenkins:
The website gets checked out from source control, and configured with a custom web.config. The main differences are that it's compiled in release mode and it connects to a database on a different machine(also a virtual machine, on the same server).
IIS is monitoring the website's directory and automatically reloads changes.
The following command is run (directories sanitized): nunit-console Selenium-Project-Dir /labels
The tests are run on the Chrome webdriver.
The selenium project uses NUnit and WebRunner.
Driver instances are created once - before all tests, in a [SetUp] attribute inside a [SetUpFixture] class. They are deleted once, in the class's [TearDown] attribute.
A sample test looks like this:
[Test, Combinatorial]
public void AnExistingUserCanLogin(
[ValueSource(typeof(Drivers), "Good")]
IWebDriver driver)
{
// This function clicks on some buttons and fills in some forms.
LoginUser(driver);
// Make sure the user is now logged in
Assert.IsTrue(driver.ElementIsPresent(By.ClassName("imgUserAvatar")));
Assert.IsTrue(driver.ElementIsPresent(By.CssSelector("a.my-profile")));
Assert.IsTrue(driver.ElementIsPresent(By.CssSelector("a.logout")));
}
(The "Drivers" class contains lazily-instances webdriver instances of FF, IE, Chrome. You can guess what the "Good" static property of the class instances)

Answer 1

The fact that it is a VM should not be a problem, and RAM sounds like it is good. What OS is being run though? Some of the Windows OS have significant speed differences between the different bit versions (because of demands on hardware). This is especially noticeable in Vista but I have noticed a difference between Windows 7 and Server 2003.
I have found that there is a huge problem if the machine running the 64bit VM is a 32bit machine. It often seems to work well for a while and then as it continues to run tests will slow down. Which should be a duh but the main thing is that there may be too many VMs being run from the same place. Other programs will be affected by this and that can help troubleshoot if your VMs are on a company farm.
The other factor that has made a significant difference is if you are running the tests against different browsers. IE8 and IE9 will take the same selenium command and run them at different speeds. I don't know why this is, I just know that I have seen it. Make sure the staging machine has the current version of Chrome (or at least the same as your dev machine).
How the staging machine is networked to the database might be making a difference. This seems like a very small chance but if there is firewall crap between the two VMs that can have significant impact on time.
The only other thing I can think of that might be changing the length of time is if there are other programs being executed on the on the staging machine at the same time. Checking the CPU usage might helpful. Personally, I have noticed that my VM uses a lot more of the CPU than my personal machine. If this is the case the only solution I have found so far is to give the VM more processing power or to only run the test and nothing else.
Good luck!