eM Client regularly unresponsive while typing email

I am typing an email, and while doing this every couple of seconds (a few to 10’s) the interface freezes for a few seconds. The cursor disappears briefly and there is no visible response to keystrokes. After a few seconds, the keystrokes are all applied and the program responds again.

I tried disabling automatic spell checker, this seems to improve the responsiveness though it does not completely seem to solve the issue.

Further, one by one I shut down all other running programs and some services which were using come CPU cycles to make sure the system wasn’t held up by something else. This does not seem to be the case, it points towards eM Client.

I do not experience this behaviour in other programs (e.g. while typing this post).
I am using Windows 10, updated to latest version.

There may be some bottleneck if the database is stored on a mechanical hard disk, especially low RPM disks. Or if the database is stored on a USB, or remote media like a server share. For best results, the OS, application and database should be on an SSD.

It may also be that you have set the sync interval for calendars and contacts to a too small interval. Go to Menu > Settings > General > Synchronization, and make sure that the sync interval is set you about 20 minutes. See if that makes any difference.

Something else that previously affected performance was the Conversation mode. Disable that using Menu > View > Conversations > Disable Conversations, and see if there is any difference.