Sean

I just tried that lh3 one by clicking the link and it worked very here.  No where near as impressive as your speed, but fast for me considering I did this with the 2 bar 4G signal I get at my workplace:
 

 
That's also the quickest I've seen on 4G with TestMy, so I'll bookmark that one.
 
Even still, that's over twice the speed my workplace can get on its rather expensive business DSL connection as this area does not have VDSL yet.
 
Thanks for this tip.

You'll still be able to test with Google's servers just not the exact same way.  You'll have to use the Mercury Speed Test system.
 
Here's one that works awesome for me all the time. lh3.googleusercontent.com Mercury Speed Test
 
Result I just ran on my laptop... 

 

 
Using that same test on one of my commercial connections I was able to see nearly 600 Mbps, again... confirmed by the client network controller.  Google has very fast bandwidth and very quick responding servers, ideal for this test.
 
You can search the Mercury index for other Google Speed Tests or make your own to nearly any web server you want to test against.  Not many people realize that TMN does this.  Find one that works good for you and bookmark it.  If you like the Google tests, go to the Google Speed Test page, scroll down and click "Custom Index"... then when you visit testmy.net/mercury it will show your favorites.  You can custom index by city, state, country or ISP (that the test is hosted on).
 
Happy Testing!

I would add a few points to this case which has mostly been explained by other members already.

The peak throughput of a router is definitely finite and quite small relative to a desktop computer. It is a separate from the throughput and power of the wireless radio interface. I was able to find that this router has a 384 MHz CPU in the latest documented revision, and has been tested to deliver 60-80 Mbit over wireless. Wired performance, surprisingly, wasn't tested, but is at least 130 Mbit. Many people nowadays consider router to be synonymous to an access point, which is not at all the case.

I think the most bandwidth hungry devices should always be connected by a cable if at all possible. Several wired devices connected to a network switch can all transmit and receive at the same time. Only one device can transmit over wifi at any given time, similarly to how it was with Ethernet hubs, which are now obsolete.

The "extension channel" allows the radio to use more bandwidth with stations (laptops, computers) that support the mode. A regular channel is 20 MHz wide, and supports at most 55-60 Mbit of throughput under "N". With a chanel extended to 40 MHz, a throughput of about 110-120 Mbit can be reached. (gross air rate 300 Mbps what is getting quoted on packaging to make the device sound more impressive). The entire spectrum allocated to wifi is 80 MHz wide, and can fit 3-4 access points with 20 MHz channels with minimal interference between them, but only 2 using extension channels.

I always use manual channel selection. Most consumer routers do not allow full control over the channel in the 5 GHz band due to legally required "radar detect" function. They may hop to a different channel automatically. Professional devices do not have that restiction, but user is required to enable "radar detect" by law. There are certain applications that allow to scan the wifi spectrum and create a graph of other signals and interference. They're built into good routers, from Ubiquiti/UBNT and Mikrotik. In the 2.4 GHz there aren't that many channel choices. Staying on channels 1 or 11 is usually the smartest option to avoid users of chanel 6 and microwave ovens.

Channel 13 could be a good choice if all your computer support it. Since that channel is not allowed in the U.S., some wifi radios have it disabled. In order to enable it on my Atheros card, I had to download the driver that comes with CommView for WiFi and change the country code on the card. My first attempt locked up the system...

For bandwith testing purposes I like to use the free FileZilla FTP Server. I have installed it on all my Windows computers to do file transfers, which also conveniently allows me to perform speed tests between any pair of computers. I can choose to send 1 file or do a few simultaneous file transfers. Paired with FileZilla (client) the program can saturate any connection. Other clients may have lower performance, and Windows SMB/Network Neighborhood is usually slower and more difficult to troubleshoot and tweak. (You can't swap out to a different version of SMB client/server without reinstalling Windows.)

I found this good article explaining wi-fi settings like channels and transmit power. They are not specific to DD-WRT.

http://www.dd-wrt.com/wiki/index.php/Atheros/ath_wireless_settings

About spectrum outside the unlicensed band and wifi devices that support using it:

http://www.qsl.net/kb9mwr/projects/wireless/modify.html

That sure is a bummer, as their CDN performed very well.    
 
The only other CDN I've had experienced with is CloudFlare, which the website Myce used about two years ago.  However, its performance was awful at the time.  Even when I tested its free service on my blog, not only did my pages take longer to load, I received notices from Google that my pages taking excessive time to load!  Myce is using PageSpeed since, so that's going to be a pain looking for a good alternative.
 
Based on my testing so far with TestMy, I'm fairly sure my ISP does not have great peering.  I visited a friend yesterday who has Sky broadband with FTTC (VDSL based), so took the opportunity to run a few speed tests.  It achieved roughly 70Mbps down whether I chose the linear UK or multithreaded and 18Mbps up.  On my home ISP, I typically get 2 to 3 times quicker results down with the multithreaded Google CDN test than the UK servers.  
 
The following are in the order of UK linear, UK multithreaded and Google CDN:
 
  
 
For comparison, the following are the UK multithreaded (left) and UK linear (right) tests I ran on my friend's connection yesterday:
 
 

Based on my experience using the Ookla Speedtest mobile app, the Android app can't be trusted!
 
Have a look at the following two tests run on my mobile (OnePlus One):
 

 
The following is the router's DSL status page which I ran both tests with:
 

 
Notice the overinflated uplink result in the Speedtest app result vs. my DSL line speed.
 
On my fixed wireless ISP connection, it underrates the downlink:
 

 
As I don't have access to a status page showing what my Wireless ISP is limited at, I ran an FTP test right after the following tests completed:
 

 
3.4MB = 27.2Mbps, so it's obvious which result is more accurate.
 
These are the results form a YouTube video I created showing these tests in action.  Usually the Speedtest.net app reports about 50% above my actual uplink for any connection, but in this case it was out by over 3 times the link speed!  Plus catching it in a screen recording made was even more exciting as I think I only ever seen it go that high once before.
 

Good explanation.  I'm sure very few (if any) connections required a test block size approaching 100MB at that time, whereas now some some of the bigger towns are getting 1Gbps fibre.  I'm only just learning MySQL and PHP.
 
I see you fixed it.     The result I posted on another forum now also shows '96kB'.
 
I remember a few years ago I tried reporting a bug to Ookla about its Speedtest app reporting faster uplink speeds 2 to 3 times faster than my DSL's physical link speed and they came back asking me to run more tests with other servers to confirm its not a problem with my Internet connection.   Obviously if the test result is reporting faster than the physical link speed, it's not an ISP issue.

That's pretty 1337.

Imagine the L next to the K is an extension of the K... another K cloaked behind.

I admit I'm running quite a lot of tests also using the automated tool, testing a recent fixed wireless ISP I subscribed to.  Its an ISP that requires multiple tests as its speeds are completely all over the place.  My existing DSL connection is consistent, but slow (actual link is 5Mb down / 0.3Mb up) and the new one claims to offer 50Mb down / 10Mb up, but intermittently struggles to offer 1/10th that.
 
While checking over the results, I came across the following one which I actually tested over the Three mobile network while I was at my workplace:
 

 
On the test results and share result page, the capital letter 'i' appears as a the lower case 'l':
 

 
Although I regularly use VPN connections either to connect to work (from home) or get around geographic restrictions, I was not using a VPN to cloak my connection at the time.

My current fixed wireless ISP Bluebox (Ireland) experiences this issue also, particularly when downloading from UK servers.  If I download a large file, I typically get 1MB/s, but if I use a multi-threaded download manager, I can get up to 2MB/s and sometimes higher. 
 
From what I heard, Speedtest does a multithread (without saying) and sure enough it reports 15.1Mb/s for me even when I rarely get this on a single transfer.  With this site TestMy, I'm getting 8.1Mb/s in the standard download test and 13.2Mb/s in the multithread test using the UK server, which more closely matches my download experience.
 
In the evening, the variation is much greater for me where a multithreaded transfer can be 4 times faster than a single transfer.  While this is fine for downloading, it sometimes affects HD playback on streaming services such as YouTube which stream with a single connection.
 
On my workplace DSL connection, I get 11.9Mbps with both the single and multithreaded tests.