I've read here about issues with Spotify, but never installed it.
So I thought I would add the following (if there could be a conflict)
Last app updates before El Capitan: Sip 3.1.1, Todoist 6.2.2, CloudApp 3.6.0, Safari 9.0
updated: uninstalled Sip, Todoist and CloudApp; Fireworks still broke
The fact is that Fireworks is not compatible with the latest version of OS X, and even in the previous version of OS X all sorts of glitches occurred (Spotify getting in the way, etc.). No more updates, no more FW development = that is the reality.
The only way to get it to run smoothly on the latest OS X is to run it inside a Windows or older Mac virtual machine such as Parallels or Virtual Box.
And at some point I guess we have to decide to just allow Fireworks to die, and move on to other applications. Part of life, isn't it?
I have similar issues.. such a shame as nothing does as good a job as fireworks...