Safari occasionally becomes unresponsive for 1 - 5 minutes at a time

Hi,

I have MacOS running Sequoia 15.4, and I've been having a problem with Safari becoming completely unresponsive a few times each day, with the unresponsiveness lasting for usually between one and five minutes at a time. What typically happens is this:

1. Safari is running normally
2. All Safari window displays turn into blank white windows, and iff videos are playing, all audio stops as well
3. During this time, the URLs are still displayed in the top entry area, with their blue progress indicator bars stuck at a low loading level
4. While this is happening, I can continue to use my Chrome browser to access the internet, and I am often able to access the same pages that Safari was previously displaying before all of its windows went white
5. After a few minutes, all of the Safari windows refresh to their previous content, as if nothing had happened.

Since Chrome continues to work while this is happening, this doesn't seem to be due to an interruption of internet service, unless it's a very brief outage that trips up Safari, and causes Safari to do some sort of diagnostic that prevents the page refreshes from happening quickly. I phoned Apple Technical Support about this, and their conclusion was that I should remove my Avast antivirus app. I removed the app, after which Safari worked fine for a couple of hours, but then the same issue reappeared. Is this something that others have encountered, and if so, have you found a cause or fix for this?

Thanks,

Ken