Today I coded something I've been dreaming about for many months - a solution to the #ActivityPub scaling problem.
The problem is that if 20 people cast 5 votes and those votes are federated to 500 servers, the instance hosting the community needs to do 20 * 5 * 500 = 50,000 network requests.
The solution is to bundle the activity up into chunks. I describe the solution and how #PieFed does it here https://peertube.wtf/w/v5aWpxjS2P4pJSn62a2AYG (probably only of interest to developers).