It looks like the performance problem is caused by the large number of tabs in this project. When we launched the interactive tabs feature, we took on some overhead for previewing tabs and making them editable. It looks like there are many circles in this project that are set up to use tabs (which is the default for an outline shape that goes all the way through).
When I select all (cmd/ctrl+A) and uncheck “Use Tabs,” Easel’s able to respond normally. You might then be able to selectively turn tabs back on just for the shapes that need them.
We’re going to look into improving the responsiveness with this many tabs. It’s not acceptable to us that this is happening.
Jeff