Nostalrius Begins - Quality wow vanilla realm (1.12)

If you're like me you are likely experiencing one or more of the following issues. Low FPS, high latency, and general lag.

A few things to get across before we continue. If you're hardware is not up-to-date or your ISP provides a poor connection following this guide will do nothing for you.

FPS

1) Close other programs
2) Update your drivers
a. Download and run Driver Booster to update your drivers easily, avoid spamware during install.
3) Uninstall unnecessary programs
a. Many times programs we never use actively run in the background. This can be software that came with your computer or video editing software you installed but never used. If you don't use it, remove it.
4) Defragment your drive
a. Use your built in OS tool or download a free one. I recommend using Smart Defrag
b. This can take many hours so be prepared to wait.
5) Remove malware, rootkits, and viruses
a. Malicious software can slow your computer to a crawl. Clean it up.
b. First do a complete scan with Malwarebytes
c. Do a second scan with Hitman Pro to find stuff Malwarebytes may have missed
d. Now do a complete scan with your favorite Anti-Virus. I recommend Baidu Anti-Virus It is free and a great anti-virus.
6) Lower WoW video settings
7) Nothing worked so far? Maybe it's time for a new computer.

Latency

1) Limit bandwidth to other programs while gaming
a. Use a program such as Netlimiter to throttle bandwidth usage of background programs while you are gaming.
2) Follow steps 1) 2) 3) and 5) mentioned above.
3) If you are not in Europe the culprit lies with the distance between your computer and the host server. Nostalrius is hosted in Western Europe.
a. Get a VPN. I recommend IPVanish Pick a European server and you should see your latency drop immediately.
b. READ: Only get a VPN if your ms is above 300 and you have tried everything above. You can inadvertently increase your latency if it is below ~300
4) Upgrade your connection, contact your ISP.

I'll go down your list and tell you what I think.

1) Closing other programs will only help if they are using CPU or if you are running low on RAM.
2) Updating certain drivers (chipset/graphics) can definitely help.
3) I would never recommend having a program download and install the latest drivers for you...unless it is a paid program like Treexy Driver Fusion.
4) If you run a HDD, then defragmentation can help a little. But only really with load times. Once everything is loaded it's in memory anyway. Don't defragment an SSD.
5) Removing viruses can help. Especially if you have trojans. They may eat a lot of CPU and some bandwidth if you are part of a botnet.
6) Lowering graphics settings is a given.
7) Not just a new computer. A custom built gaming PC.

Latency

1) Don't download anything while gaming if you care about your latency.
3) The only reason a VPN server in europe would help is if your ISP's routing to the server is less efficient than the VPN server's routing. In general a VPN will raise your ping, not lower it.
4) If you already have cable/FiOS then you can't upgrade to a connection with faster pingtimes. You can upgrade your plan to get more bandwidth but your latency in game will still be the same.

I own couple of computer/phone repair shops in Houston. I've used Driver Booster many times when DriverPack fails. It's free, it works, and it's error rate is extremely low and usually only fails on older computers where newer driver versions cause errors.

You said it yourself "Closing other programs will only help if they are using CPU or if you are running low on RAM." So my step is still valid.

The game is always loading new content which can attribute to low FPS, defragging can help.

I mentioned avoiding getting an VPN unless the latency was extremely high "Only get a VPN if your ms is above 300 and you have tried everything above. You can inadvertently increase your latency if it is below ~300" IPVanish is a tier 1 service but it would still add ~150-200ms so yes, as you said it all depends on the ISP routing efficiency.

4 was aimed more towards people who have been under the same plan for a decade getting 1mbps. I've seen it many times. ISP fails to notify of speed upgrades even at the same price level.

PS. I enjoyed your guide How To: Maximize Quality and Smoothness