Bug report sent. This was with the currently installed 5.2, with which I can also reproduce the problem. Will try again over the next couple of days with 5.3 and 4.7 for comparison.
Update: I found the installer I'd originally used to install 5.2.3.1205 last year before I replaced the hard drive and had to reinstall the OS. This version is also runs quite slow now, but at least is fast enough to be more or less usable for the time being. I will observe its behavior for a few da...
Having basically the same problem with version 5.3 - so slow as to be practically unusable, and intermittently stops responding altogether. In shutting down or rebooting Windows often has to kill it because it won't exit. I've since downloaded 4.7 and installed it and it seems to be working fine, al...