Flash cs5 takes about 3 minutes to start, it seemes to hang or slow down when "initializing tools" and "initializing fonts" and the "spinning beachball" appears during these two.
I tried reinstalling, launching the application from a new user account, repairing disk permissions, updating the application but nothing changes.
On the other hand, Dreamweaver and Photoshop (CS5 also) load almost instantly.
My computer is a 2.54ghz core 2 duo, 4gb Ram macbook pro running 10.6.4, all updates installed.
I figured it out. For me the problem was my very large font library existing in both the user font folder and the system library font folder. Once I deleted the duplicate Fonts from my user library Flash returned to normal. Everything works great now.
I have found that opening an .fla that was created on PC seems to make Flash CS5 responsiveness issues magically go away - until Flash is closed and reponened. I plan to keep a PC generated .fla always available.