Very Slow Page Loads in CI4 on Localhost

I've been developing a couple of apps using CodeIgniter 4.2.3. They both ran fine until today, and then (seemingly out of the blue) started loading extremely slowly (> 2 1/2 minutes per page). 
The apps each have simple databases with very few records, but the long load times only seem to affect the dynamically generated pages. I've tested with some static content and those pages load immediately. I hadn't changed any configuration settings or anything on the database end. 
I restarted Apache and MySQL more than once. I rebooted my machine a couple of times. I even started a new CI4 project with a fresh database (but used migrations from one of the projects to create the structure), and have the same issue. 
Weirdly, I have a couple of even simpler database driven CI4 sites that I built a couple of months ago that seem to be fine.
I have tested using Chrome, Firefox, and Safari, all with similar results.
Any ideas or suggestions would be warmly welcomed!
Thanks
Stevie

So I discovered that this was nothing to do with CI4, but due to network (probably DNS) issues, that were crippling embedded CDN script loads.