DNN Optimization Steps

1. Increase it's performance by deleting it's logs. To do that, login to your DNN site as HOST. Then go to "Admin" > "Log Viewer". Then in the log viewer page , there are "Delete selected exceptions" and "Clear log" link at the bottom of page.
2. Another faster way would be connecting to your DNN db directly and run the following command: - delete from eventlog.
3. Deleted blank spaces in default.aspx file.
4. Deleted blank spaces in skin file,Javascript file.
5. Startup performance can be increased by going to the Site Configuration settings and disable the Logging feature (by setting Logging to "0" in Site Settings or Host Settings)... obviously, this could be done if you don't need a logging feature (and I don't need it).
6. Disable scheduler mode host>>hostsettings>>advanced settings
7. Use the release.config from the DNN package
8. Ensure that DNN does not run in debug mode : LI>
9. Enable HTTP compression (http://www.dotnetjunkies.com/Article/16267D49-4C6E-4063-AB12-853761D31E66.dcik)
10. ‘Host’ -> ‘Host Settings’ -> ‘Advanced Settings’ -> ‘Performance Settings’ -> turn on the Compression and Whitespace filter options. Don’t use this option if you have installed any SSL manager module for DNN or if you want use the internal skin, template or css editors.
11. 
    Set debug mode to false: .
12. Check if the DNN caching is enabled: ‘Host’ -> ‘Host Settings’ -> ‘Advanced Settings’ -> ‘Performance Settings’ -> Select ‘Moderate Caching’ or ‘Heavy Caching’ from the ‘Performance Setting:’ drop down list.
13. (‘Host’ -> ‘Host Settings’ -> Advanced Settings’ -> ‘Other Settings’),Select ‘Database’ for ‘Site Log Storage’,Active the ‘Disable Users Online’ checkbox.
14. More than 50% of all DNN page content is Viewstate. To remove the Viewstate from the page content, go to: ‘Host’ -> ‘Host Settings’ -> ‘Advanced Settings’ -> ‘Performance Settings’ and select ‘Memory’ from ‘Page State Persistence:’ radio button list. This will reduce the page loading time up to 50%.
15. Some hosting providers unload the DNN dll's after a certain time to save CPU time on their shared hosting environments. Also DNN deletes the cache after a certain time. This can be bypassed by SmarterPing by SmarterTools.SmarterPing by SmarterTools keeps DNN sites up and running and it does a great job. If you ping DNN URLs it dramatically improves the performance of DNN. Set SmarterPing to ping 4 or 5 key areas every minute. The loading times are 4 or 5 times faster.If there are any problems after you have changed this parameter and you can not go back because the update host settings button doesn’t work, perform the script below via Host -> SQL or SQL Web Admin:update hostsettings,set SettingValue = 'P',where SettingName = 'PageStatePersister'.
16. Restrict the number of Log Types -> ‘Admin’ -> ‘Log Viewer’ -> select ‘Edit Log Configurations’ from the module menu -> delete all unimportant items.

Telerik RAD Combobox doesn't work in DotNetNuke (DNN)

Firebug confirmed that it was properly populated, but i couldn't make it to drop down. Turns out i had "Supports Partial Rendering" option unchecked in the View control of my module. Allowing partial rendering resolved the dropdown issue.
Here's how to do it:
1. Login as HOST
2. Go to Host > Module Definitions
3. Select your cutom module from the list
4. Scroll all the way down and select your VIEW control
5. Check "Supports Partial Rendering" checkbox
6. Click "Update" link
Hope this helps

After Upgrading My Site I Can No Longer Log In

Not being able to log in after a site upgrade can be a traumatic experience. Rest easy - it usually is simple to fix.
The first thing to check is that you copied over your MachineValidation and MachineDecription keys from your previous web.config. When upgrading one of the steps you need to perform is to move all your custom settings from your old web.config to the new version, and these keys can be easy to miss.
If you still can't login with the old password after that, try registering a new user on your site. After doing so you can query the dbo.aspnet_membership table to get the password and passwordsalt from the newly registered user. Next update your host user's values with these new values. Now you should be able to login with the new user's password.

If DNN 4.X search is not working follow these steps

1. Changed the contents of site
2. Run this script
   truncate table {databaseOwner}{objectQualifier}SearchItemWordPositionDELETE {databaseOwner}{objectQualifier}SearchItemWordDELETE {databaseOwner}{objectQualifier}SearchWordDELETE {databaseOwner}{objectQualifier}SearchItem
3. Then under host menu selected "Search Admin " and clicked on " Re-Index Content" link.
   And after that new contents starts coming in search.

If you want that DNN search engine automatically index contents when there is any change in site content then "scheduler for search indexing must be running" .