Web pages taking long time to load

Web pages taking long time to load. Example: For several years I have been entering the serial numbers of dollar bills on a web site called Wheresgeorge. I would enter one and withing a few seconds, another page came up to enter another. Within the last few weeks that has changed and now it takes 50 to 60 seconds for this page to change every time.
Sometimes, when I click to open my home page (yahoo.com) it takes a long time to open and sometimes it loads only the top part with the address bars, then will not load the bottom part with the usual pictures, links and news items like normal.
It is the same on my desktop, my laptop and my wife's laptop. (She doesn't have a desktop)
Don't know what could be causing this or how to fix it.
Here is the information about my system that you ask for.

Tech Support Guy System Info Utility version 1.0.0.2
OS Version: Microsoft Windows 7 Home Premium, Service Pack 1, 64 bit
Processor: AMD Athlon(tm) II X4 630 Processor, AMD64 Family 16 Model 5 Stepping 2
Processor Count: 4
RAM: 4094 Mb
Graphics Card: ATI Radeon HD 5700 Series, 1024 Mb
Hard Drives: C: Total - 476837 MB, Free - 423349 MB;
Motherboard: Gigabyte Technology Co., Ltd., GA-MA74GM-S2
Antivirus: Microsoft Security Essentials, Updated and Enabled