I have a MiKTeX installation on Windows 10 on a relatively powerful machine. A few weeks ago, TeXworks started to hang on startup. It now takes up to 25 (!) minutes when starting and consumes about one-and-a-half cores of my CPU while doing so:
I have no idea what it is doing during this time.
When it is finally open, every attempt to run pdflatex is painfully slow. Everything happens like in slow motion, with the main window not reacting to mouse clicks or keyboard input (but it finishes eventually). Building an empty sample document takes about 5 minutes. I have not yet found out how long it takes to successfully close TeXworks - I gave up waiting after one hour.
The rest of my computer works fine. TeXworks has been working on this machine for several years without any issue. I updated to the latest MiKTeX version without effect. I also completely uninstalled MiKTeX, rebooted and reinstalled the most recent version. TeXworks is still unusable.
I cannot find any log files or even hints about what could be wrong. Google and SE searches returned nothing apart from 10-year old QT bugs which seem to be unrelated. How can I find out what is wrong with my MiKTeX installation and how do I get TeXworks working again?