Loading a big graph completely freezes the IDE
IntellIJ uses asynchronous tasks for things as simple as pasting code, so a CPU intensive task like computing a graph should definitely be offloaded to another thread.
I'm also running into this. I have 5000+ line .dot files and PyCharm locks up for several seconds opening them. It's a bigger problem because of the one-click preview they introduced a while back. Need to offload the processing, or if it's possible, force PyCharm into just the editor view, so it doesn't have to render the diagram.
Same issue reported in https://youtrack.jetbrains.com/issue/IJPL-175271. A sample dot file can be found in https://github.com/pydot/pydot/blob/main/test/graphs/b106.dot