why is my Visual Studio 2019 Pro so slow debugging, after doing Visual Installer update?

Question

VS2019 was working fine. Then I ran Visual Installer and added "Mobile development with .NET". After than, visual Installer "update" button was showing, so I did the update.

But now when I stop my VS2019 project at a breakpoint, single stepping is very slow, taking many seconds per step. Tried restarting VS2019, and restarting my Windows 10 Pro, but got same slowness.

Opened same project with VS2017, it is debugging is OK, no slowness.

Answer 1

Comprehensive deletion of all contents of %TEMP% worked for me - https://developercommunity.visualstudio.com/content/problem/516141/very-hight-cpu-usage-by-visual-studio-2019.html

I can't believe is 2020 and MS can't stop spaffing crap into a temp directory which causes their software to slow to a snails pace with some kind of infinite processing issue. Jeez.