The message is misleading. It searches if the update can be installed or if the update is no longer needed (superseded).
Line #, DPC/ISR, Process, Stack Tag, Stack, Count, TimeStamp, % Weight
10, , , , wuaueng.dll!CUpdatesToPruneList::PopulateSupersedenceInfo, 31521, , 43,72
11, , , , wuaueng.dll!CUpdatesToPruneList::AddSupersedenceInfoIfNeeded, 31521, , 43,72
WUSA.exe, which is used to install MSU updates, is just a wrapper to Windows Update. After Windows Update installed an update it hangs again in a loop to check if updates apply or not and those checks are useless after an install and this loop blocks you from installing other MSU updates.
To speedup the Installation, stop the WindowsUpdate service via GUI (services.msc) or via elevated (running as admin) command line (
net stop wuauserv). Now the loop is stopped and updates install faster.
Install the first MSU update, stop WindowsUpdate service again and install the 2nd MSU file.
I also created a script with enums all MSU files in the same folder as the CMD and installs them and stop WU service on it's own everytime to speedup setup.