So , you are in need of a warm-up , and do not want to invest in writing and deploying a timer job as per http://msdn.microsoft.com/en-us/library/cc406686(office.12).aspx, or simply you want to keep things to a minimum …

Hmmm.

Here’s a PowerShell script to achieve what you want (the script will issue one request to your site, like you would do through IE):

$url = read-host -Prompt "Enter the URL to get ex http://www.contoso.com/default.aspx"
$wc = new-Object System.Net.WebClient
$httpRequest = [System.Net.HttpWebRequest]::Create($url)
$httpRequest.Credentials =[System.Net.CredentialCache]::DefaultCredentials
$httpRequest.UnsafeAuthenticatedConnectionSharing = "true"
$httpRequest.Method = "GET"
$httpRequest.Timeout = 300000
$objResponseReader = [System.IO.StreamReader]($httpRequest.GetResponse().GetResponseStream())
$httpResponse = $objResponseReader.ReadToEnd().ToString()

save this as WarmUp_One.ps1 and your’re all set. Whenever in need, you can run this and target it to an URL to your liking.

Now if you want to warm them all , here’s the modified version for all your web applications.

add-pssnapin Microsoft.SharePoint.Powershell
$wc = new-Object System.Net.WebClient

function Warm_UP ([string]$url)
{
write-host("warming up  "+$url +"....")
$httpRequest = [System.Net.HttpWebRequest]::Create($url)
$httpRequest.Credentials =[System.Net.CredentialCache]::DefaultCredentials
$httpRequest.UnsafeAuthenticatedConnectionSharing = "true"
$httpRequest.Method = "GET"
$httpRequest.Timeout = 300000
    try
    {
    $responsecode = $httpRequest.GetResponse()
    $objResponseReader = [System.IO.StreamReader]($httpRequest.GetResponse().GetResponseStream())
    $httpResponse = $objResponseReader.ReadToEnd().ToString()
    Write-Host ($reponsecode.StatusCode)
    }
    catch
    {
     Write-Host("Error")
    }
}

get-spwebapplication | Foreach-Object {Warm_UP($_.Url)}
write-host("all warm and fuzzy inside :)")

Save this as WarmUp_All.ps1 and execute it in PowerShell, or schedule it to run with task manager

Technical details on the functions used:

http://technet.microsoft.com/en-us/library/system.net.httpwebrequest.aspx