Well, this is a lot of panels, but not necessisarily the problem.  It would depend on how many controls are on the panels, etc.  Also, what else is going on....are you loading up data, doing other types of calucaltions, etc.  Here is the problem....even though the controls may not be rendering, they are still being instantiated.  Also, DevExpress is slower than using standard controls or even Infragistics....this is why we moved away from them is because of this very reason...they have rebasing issues and all of their themes use images rather than render.  So you will have to be a little more creative.  One thing you can do is class the pages and them bring them into the PanelManager as needed rather than having them all there at once.  Even if you were using standard controls...though it would be faster, it would still be slow if too much is happening on one form.  So look at your form and see if there is a way for you to split things up.  You can also get something like the Ants Profiler and run it against your application and it will tell you how long every line of code is taking and give you exact indicators of where your problem spots are.

Just an aside question about DevExpress....we've been having a lot of problems with slow load times and are trying to figure out if this is something that is coming from DevExpress.  You said that you moved away from DevExpress and to Infragistics because of the speed issues.  How much of a difference did you see in the speeds between the two?  What can I do to positively identify them as the issue or not?  I know we are using the Layout control extensively and they are telling us that it is definitely slow, but they are working to improve it in the next version.  Hopefully this will give us some help here as well.  I guess I'm just worried that we made the wrong choice with using DevExpress and now we've done so much of the UI it would be a nightmare to start over with a different control.

This is kind of like asking, "how long is a string."  You need to find where your speed issue truly is and then go from there.  Yes you have a lot of controls on the form, but that may not be your primary issue.  When we run into problems like this we begin disecting things until we discover the slowness.  One good tool to help this is the Ants Profiler from Red Gate software (http://www.red-gate.com/products/ants_profiler/index.htm).

This is why we created the Application Theme features in StrataFrame, so we have control of the application aesthetics and render time.  We are only using Infragistics controls for things such as spell checking textboxes and currency editors, etc.  Everything else we are using our own controls for our medical system.  To put into perspective, rewriting portions of our application that were using the DevExpress controls versus our controls (in conjunction with some of the Infragistics editors) was more than twice as fast loading and in some cases 3 to 4 times.  This was especially true for the first display of the control or form.  Does the same form come up faster the second time it is launched while in the same session of your application?  If so, then you definitely have assembly loading and rendering problems.

In short, we moved away from DevExpress because it dramatically slowed down the application.

I understand how you feel.  This is why you need to truly understand where your problems are.  It is frustrating, but it is better to correct a wrong now rather than down the road.  I am not saying the DevExpress is the wrong choice as they have some good controls and tools, but if you are experiencing very slow performance, it would be a good idea to think about this. 

You may also just want to think about how to restructure this form you have been discussing because I think that you have some design issues here as well that could be hindering performance.