Shotcut now crashes with every click

Well, that is good progress.

We have found that the timeline performance can be poor for some users - while it works great for others.

There are some recent comments here:

Some things I would suggest to try:

Disable Audio Waveforms:
Timeline Hamburger Menu → Options → Show Audio Waveforms

Change Display Method (try the options in this menu):
Settings Menu → Display Method →

As a test, try turning off Antivirus (this is just a test, I do not recommend running without antivirus)