Slow operation on Win 10 Surface 3

I’ve been using eM Client (7.1.30453.0) problem free on a Win 10 Pro (Version 1703) for a year or so without problems. During the last 2 weeks or so, it has consistently been very slow to respond on any actions.

I’m using the application as a client for a G-Suite IMAP address and, when opening an email from the inbox, it will show a black window with a … is not responding error for 10-20 seconds before opening properly, and often it will not show the contents of a message as it believes it is offline, when it is connected.

Moving mail from the inbox to folders using keyboard shortcuts is also problematic, and slow.

I’ve checked CPU usage and RAM, and nothing seems to be an issue, and I use eM client on a different account/Win 7 machine with no problems.

Any thoughts?