One way is to exclude some dll from EPiServer Framework scanning process (http://stackoverflow.com/questions/16550827/what-does-forcebinfolderscan-attribute-in-episerverframework-config-file-means/16560302#16560302) but from experience that will not give you significant improvements (unless you have huge list of libraries those really does not contain EPiServer related stuff).
Which browser are you running? I'm running my development environment with a bit over 1000 request (without any minification/layer packaging) with a load time around 4 seconds in Chrome. With minified layer files I'm done to a bit over 3 seconds. Doing the same thing with Firefox adds a few more seconds so Chrome is currently the main browser for most of our developers.
The times above is given the Alloy demo site with very little content. We know that there are some performance issues when working with sites with large amounts of content and ee are currently working on improving performance for the page tree to speed this up. If you are running with content providers, you might want to know that we are currently working on a performance bug targetted for the next core patch.
one of the key settings is making sure you have enabled optimizeCompilations in web.config. There is also a tool so that you can debug if one of our modules is slowing down your system. We have done a lot of improvements and rewrote the whole scanning process in 7 to make sure its faster, see:
Im using Chrome as well, but its a bad idea to have that many requests, after all its 1000 files it needs to check file versions, read from cache etc. My harddrive at work is probably the main bottleneck here, an SSD would probably shave most of that time off, but I can't require every customer to upgrade to high-end gaming machine to be able to update their website.
optimizeCompilations made a big impact, went from about 32 seconds for a complete cold start to about 12. Why isn't it set as default?
Edit: It does seem like it was default but disappeared from the web.config some time ago when switching .net framework to 4.0 istead of 4.5.
Just some more information regarding performance and the 7.5 release:
Is there any way to speed up the episerver editor/admin part?
It seems like theres no bundling happening, and the browser makes roughly 200 requests to show toolbar which is insane! Even when i run the system locally it takes around 8 seconds to just show the basic UI which is horrible.
The cold boot is also a lot slower than epi 6. Inn epi 6 it was possible to exclude some dlls from the startup, is it possible to do something similar in epi 7.
As a developer i spend probably 60% of my days now just waiting for episerver to start from the last compilation and redraw the UI.
It's probably something that can't be fixed without access to the source code but hopefully the developers at episerver reads this and realises that they will lose a lot of customers if they dont fix this soon. A pissed off developer can easily remove tens of yearly subscriptions and tens of new customers.