Runs a solid 60 FPS in Firefox here, same as Chrome and IE9.
Apart from that please make separate .capx files created from scratch to demonstrate separate issues, as described in how to report bugs. Otherwise it's hard to tell if the other issues are mistakes in your events or issues with C2.
e cannot help with large projects with hundreds of events. These can take hours and hours to investigate, often with the conclusion it was simply a mistake in the events. Unfortunately as a very small team we simply cannot afford the time to do this. As above, re-create the bug in a minimal new project.