how to make winform forms open faster?

There are many possible solutions.

1. Is all loading you do necessary and can the loops, SQL queries, database itself (indexes) be optimized. This is the very first thing you need to do.

2. In FormLoad, use SuspendLayout and ResumeLayout to stop reloading controls on each change, but rather on a transaction of changes. (Please read up on the methods before using)

3. If it is still slow, can you wait loading controls until needed, eg. A combobox with 10 000 items will always be rather slow. What if you changed that combobox to a usercontrol with a textbox and button that opens a small dialog with the list. (of course, already filtered with the value typed in the textbox) That would postpone loading the data until you actually press that button.

4. Using NGen compilation can improve performance, but I would not use it until a last resort.

Of course there a re other things to consider: Is the network fast enough, is the hardware fast enough, do you have sufficient memory? In case of network issues, caching data might help, for hardware issues: just upgrade.

Hope this helps.