Safari slow after Catalina 10.15.7 update

On 2/09/2021, my early 2015 Macbook Air running Catalina worked just fine.

On 2/10/2021, I downloaded the very large update to Catalina 10.15.7.

Now websites that used to load quickly, now load very slowly, if at all.

I have not tested other functions but as I use this computer primarily for web browsing, it is now basically useless to me.

Problem is NOT with my wi-fi signal--internet on my phone and other PC are fine.

Please share advice on how to restore Safari to previous robust functioning. Thanks!