KB4571729, the 2020-08 monthly rollup for Windows 7, was highly defective. We reproduced its symptoms on multiple workstations. After uninstalling KB4571729, the symptoms immediately resolved on all workstations. Among the bugs:
1) Windows Update runs forever and will not find updates after installing KB4571729.
2) Windows Explorer is sluggish.
3) The network connection icon in the system tray has a blue circle that either never clears or turns into a red x, even though there definitely was a network connection.
4) Large Word documents (with hundreds of pages) will not open.
5) Under Task Manager, Performance Monitor would not open.
Even the configuration process after uninstalling KB4571729 took a long time. From these errors, it seems like KB4571729 is causing memory problems.
Today is Patch Tuesday. I hope Microsoft is aware of the bugs with its August Windows 7 monthly rollup.