Mac is painfully slow with constant pinwheels after 10.15.4 update

I have a 2017 MacBook Air - ever since the update my mac is SLOW.....constantly get pinwheel and apps hang or take forever to open.

I've already run the Disk Utility, have plenty of disk space and memory.

Please advise on what I can do to fix or please provide an update ASAP

I do notice that mDNSResponder is very active....

Thank. you