In some cases, faulty or outdated display drivers also seem to cause a right-click context menu to appear slow. The main issue seems to be some 3rd party application which seems to be conflicting with Windows Shell extensions or a corrupt 3rd party shell extension itself.
This issue is annoying because desktop right-clicks in an important function of windows which let users quickly access settings, display settings etc. So to fix the issue, first, you need to find the cause of the delay and then fix it. In short, the right-click context menu seems to be delayed because of some reason, and that’s why it appears slow. If you have recently upgraded or updated your Windows, you might be facing this issue where the right-click context menu on desktop appears to be slow, in fact, when you right-click on the desktop it takes a lot of time for the context menu to appear.