Yesterday I updated my sites from DNN 5.6.3 to DNN 6.1.2. I like the new UI and client resource management for bundling javascript files. Works great and even iproved my YSlow score. 

To my surprise the rendering of the actual aspx page has decreased a lot. On my development machine firebug measures a load time of 25 ms for my homepage. The same page renders in DNN 6.1.2 in 130 ms. Nearly 5 times slower!!! On the production machine the performance hit is even bigger. 

A performance hit was also mentioned in the following post:
http://www.dotnetnuke.com/Resources/F... 

I did some research myself on the whitespace filter suggestion in the mentioned topic. Turning this off in 5.6.3 doesn't result in slower load times, so I don't believe this causes the performance hit. Could this be a caching issue? My site has a lot of modules on it's pages an uses memory caching extensively.

I think the combination of the client resource management  with the ultra fast page rendering times of DNN 5.6.3 would be great!

Does anyone know how to fix this or can this be a performance bug in the new DNN version?

@Costa: Looks like the new version is indeed slower in rendering pages. 

@ToAll:
I set up a test environment to look into this a bit further. This is a clean install of the DNN source, so I can use the debugger to look into the code. Here are my findings:

• Adding 20 cached text modules* to a page (memory cached) increases page load time from 60 ms to 120 ms.
• Commenting ClientResourceLoader in default.aspx loads the page reduces the load time to 40 ms.
• The difference in load time between a page with 0 modules and 20 modules is reduced to 15 ms 

* 20 cached modules on a page is not uncommon for the sites we build at my company.

I tried several things in code but couldn't find  the cause of the problem. I'm certain that the increased amount of modules introduces extra load. My best bet is the Client Dependency Loader causes this.  

 I'm out of options and time :-( ...  I hope someone from DNN will pick up on this or can give me some clueas as to where to look in the code.

It would be great if we can combine the benefits of the client resurce management with fast page rendering. 

kind regards,
Jeroen