Jun
13
2010
In Flex 4, the framework RSL is linked by default, the advantage of using the framework RSL is smaller application SWF sizes and faster downloads times; the disadvantage is increased memory usage and slower first downloads times for the firt application. It’s unfair for someone who uses the framework RSL first.
The SWF size of the application with the framework RSL is smaller, but all the framework classes are loaded in the RSL, not just the classes that your application requires, so it spends more time to download for the first time. The framework RSL can stroe in Flash player cache, and it can across applications, domains and browsers, so downloads times is fast for the second tome, and for other application. But if your client is only concerned for the first impression, it will be a bad choice.
Here are some suggestions to load fast:
1. Only load necessary the framework RSL, if you use Adobe Flash Builder 4, from Properties>Flex Build Path>Library Path, select unnecessary swcs, and then click Remove button.
2. Load the framework RSL from your remote server not from Adobe. If you use Flash Builder 4, repeat step 1, open the target swc, then click RSL, the default Deployment path is on Adobe server, replace it with your own server.
The most important that I have mentioned above: It’s unfair for someone who uses the framework RSL first, so Adobe should try to store the framework RSL in Flash player cache after Flash player is installed.
原文：http://www.riafan.com/article/flex/use-rsl-carefully.html