I have an iMac with the latest version of High Sierra, when you save to the desktop it takes about 20 to 30 seconds for the file to appear, this happens with everything, screen shots, downloads, copy and paste, etc. etc.
Any help would be appreciated.
To trouble shoot further you can:
Try a SafeBoot https://support.apple.com/en-us/HT201262
Takes noticeable longer to get to the login screen, does a 5 minute disk repair before it fully boots up, and certain system caches, dynamic loader cache, etc. get cleared and rebuilt.
This test will tell you if third party interference; extensions etc are not loaded in safe boot mode. Sometimes a SAfeboot is enough to clear anomalies like yours after a restart.
Test issue in another user (or guest user) account https://support.apple.com/en-us/HT204443
This will tell you if it a universal issue or isolated to your user/admin account.
Desktop saves take long time to appear
