[crubier]

Even if Flutter existed, it would absolutely not have been an obviously smart move by Slack to DOUBLE their engineering workload by picking it instead of Electron while still having to develop a web based version. For what result? The app would most likely not be noticeably faster, if anything, just because the engineering effort that went into optimizing Slack performance would have been dilapidated in re-implementing and maintaining Slack in another toolkit.