Just something to note.
Have used Malwarebytes free, on and off, for a few years, usually just to run a test to see if it can detect things Avast misses.
Last week I updated it and run a scan - nothing found, but forgot to disable it. Over the next few days the time taken to load pages increased dramatically. For example the ThinkBroadband speed tester was taking over 3 minutes to load to the point the test started.
Disabled the Malwarebytes program and service and it returned to almost instant loading.