My analysis of the trace (trace is here, installer for the analysis tools is here, analysis tutorials are here, feel free to follow along) started with my looking at the input events and Window in Focus graph in Windows Performance Analyzer (WPA), both shown below (zoomed in a bit for maximum detail): I then sorted by Time Since Last and noticed that at one point the main thread had been waiting to run for 15.572 s. In fact it was probably waiting even longer, but the start of its wait was before the start of the trace and therefore unknowable. RuntimeBroker.exe crashed (due to heap corruption, according to the call stack in the RuntimeBroker.exe crash dump, shown to the right) and it took more than 15 seconds to upload the crash dump, presumably due to my flaky hotel WiFi.