Jan

1./ Housekeeping
Please go to step5 export, export project. This will create an iwzip file. This is a self contained backup which can be imported directly or could even be imported to a new PC complete with all content. In case of difficulties or corruption of the project this is a very robust form of backup, far more reliable than the built in backup routine. You can rename each iwzip or in recent versions the iwzip can be renamed at the time of creation so you can have multiple versions.
The built in backup has issues, but most of the time it is a handy recovery option. Click the down arrow next to save and select create a backup copy every time you upload (oddly this is off by default). When working, frequently click the down arrow and create yet another backup.
2./ Delays and apparent freezing in WX5 can be caused by empty cells on web pages (especially when using row formats feature). If you have unnecessary (unused) rows or columns of cells, delete them. If you will require them or need them to maintain the layout, add an object to every empty cell (eg text, html, etc), there is no need to add content to these objects.
3./ If difficulties are experienced on or after preview (especially with large projects), hold ctrl key down when you press preview. This will force a full update of your site before displaying the preview.
4./ If WX5 becomes unstable after update or upgrade, temporarily uninstall or totally disble any 3rd party anti-virus, malware, firewall or vpn. This will rule out WX5 functionality being mistakenly blocked by these apps. You should also disable one-drive in case it is attempting to synchronise the Incomedia folder. If you have any doubts about software that may be on your PC, run malwarebytes, superantispyware or similar and then uninstall when complete.
5./ Still problems? Ensure all projects are worked on locally. Working across a network, on external USB devices and cloud based or synchronised services can wreak havoc.
6./ If WX5 is still unreliable then perhaps the problem is hardware related, perhaps a faulty sector on the HD. You could run scandisk from Windows or create a DOS prompt as administrator and run chkdsk c: /r for comprehensive check and repair.

Please advise if this helped. NB point one will protect you (export project often), point 2 will hopefully fix the issue.