WiFi appears healthy, yet browsers fail to load pages intermittently, and more...?

You may have four bars on your wifi connection, but that has nothing whatsoever to do with the speed at which you connect to Internet web sites. Wifi is only taking you from your computer to your router, i.e. to the room next door. Unless something breaks in your router or laptop, or if you are too far away, or there are thick walls between you and the router, you will always have good wifi throughput

Your throughput is very dependent on the DSL connection between your router and the access point in the exchange of your provider. It is also dependent on the connectivity between your provider's equipment and the Internet backbone, and finally very dependent on the capacity of the web servers you are hitting.

You may want to investigate a little what is happening when your performance goes down. Is it at specific times of the day ? Is it with specific sites ? Is someone else using another computer when that happens ? Check the devices connected by wifi. Make sure they are all accounted for. It could be that a neighbor is piggybacking on your wifi and stealing some bandwitdh. Unlikely, but possible.

You may also want to measure your actual throughput using tools like http://speedtest.net/ at different hours.

you probably did not specify which browser you're using. even if, maximum persons ignorantly use internet explorer. it sucks. horribly. supply up using it. and basic it on hearth. change to firefox. goodluck. :)