If you’ve been playing with Flex sans Flex Builder, you may have experienced very slow compile times using mxmlc via command line. Very slow. Go get the Flex Compiler Shell, also known as fcsh. It speeds things up. A lot. Easy to get going: just copy the necessary files from the zip’s bin to the bin in your sdk location (it’s explained on the download page I linked to).
fcsh is the reason that Flex Builder compiles so much faster than using command line mxmlc.
Why is it so much faster? Here’s what the folks at Adobe Labs say:
One reason is that by keeping everything in memory, fcsh eliminates the overhead of launching the JVM and loading the compiler classes. Another reason is that compilation results (for example, type information) can be kept in memory for subsequent compilations.
This utility is intended to improve the experience of users of the command-line compilers. If you are using Flex Builder, you do not need to use fcsh. The Flex Builder tool already uses the optimizations provided by fcsh.
For simple applications, fcsh might not be necessary. But for more complex applications that you compile frequently, you should experience a significant performance improvement over using the mxmlc and compc command-line compilers.
Oh, and the application I’m working on doesn’t get much simpler. It might not be absolutely necessary, but the noticably faster compile times make flex play much, much more pleasant.