Not something I am familiar with, but server round trip delays post update are often caused by older addons or third party scanning tools on your computer. You could try running Thunderbird from the help menu in troubleshoot mode and see if anything changes.

Hello, Matt In Troubleshoot Mode, the problem remains; that is, it takes from 4- to 7-seconds for deleted emails to disappear. Historically, they have generally disappeared within one second of selecting Delete button. This is a new issue that began perhaps 15 July. No new programs, add-ons, or security software added. The only changes are the frequent Thunderbird revision updates, of which, the current one is 102.13.0.

The utility Glary Utilites Pro, has not corrected the problem either.