In our review of ASUS' Eee Pad Transformer Prime I mentioned that I couldn't sustain speeds greater than 2Mbps over WiFi on my review unit. In practice, most web pages loaded at a meager 0.5Mbps. ASUS insisted the problem was limited to my unit however CNet referred to a similar issue in their testing:

Unfortunately, during the review process, we experienced some very suspect performance issues (detailed below), which led us to believe we were possibly in possession of a faulty unit. So, we are going to hold off on giving final ratings for the Prime, but check out our initial impressions.
At the same time, I had test data from both ASUS and NVIDIA that show the Prime is capable of reasonable WiFi speeds. Yesterday morning I received a replacement Prime which was tested prior to being sent my way. The good news is the 2Mbps cap and poor range are both gone, the new sample is much faster on WiFi. Clearly there was something wrong with my original unit and it's being sent back to ASUS today for an autopsy. The bad news is I was still getting numbers around half of the original Transformer.
Using Ookla's web app I get a consistent 34 - 37Mbps on the original Eee Pad Transformer (our actual WiFi performance tests involve downloading a file from a local server, but Speedtest was a quick and easy way to verify the problem). My original Prime review sample averaged around 0.5Mbps, while the replacement Prime got around 10Mbps - all in the same test location. Fiddling around with location I could get the replacement Prime up to 16Mbps. My test area is riddled with challenging interference so I setup a separate test area in another room. Even after buying the same Netgear WNDR4500 wireless AP that ASUS verified 31Mbps+ operation on, I wasn't able to break 16Mbps.
I have four other APs covering my house, I turned all of the radios off as a last ditch effort. Boom - 36Mbps on the Prime.
The culprit appeared to be either my 3rd gen Time Capsule or 5th gen Airport Extreme, with those radios off and using the WNDR4500 I was able to get performance competitive to the original Transformer. Here's where things get interesting. The original Transformer was made out of plastic, through which RF travels quite nicely. The Prime's metal construction makes things a bit more finicky. Indeed this is exactly what I saw, where depending on tablet and AP orientation I'd see anywhere between 10Mbps and 36Mbps downstream (average speed tended to be in the 15 - 20Mbps range). Apple gets around this issue in the iPad by putting the WiFi antenna behind the plastic Apple logo, however it's not entirely clear to me where the WiFi antenna is on the Prime (I have this policy about not taking things apart until I'm done testing them).

As to why performance was lower with the Apple APs active, I'm not entirely sure. Chasing down RF interference issues can be a severe undertaking. One thing is for sure, the Prime is going to be far more finicky than its predecessor when it comes to reaching peak speeds over WiFi. 
WiFi performance isn't the only thing that improved with the new unit - I'm getting much better battery life as well. Our video playback battery life test doesn't have anything running in the background, but we are actively connected to a WiFi network throughout the duration of the test. As I surmized in our review, it's possible that whatever was causing the WiFi issues also had a negative impact on battery life. Curious to find out if battery life had changed as well as how the TF Prime did in its Balanced power mode, that's the first test I ran upon receiving the new review unit. Things are starting to look a lot better:

Video Playback - H.264 720p Base Profile (No B-Frames)

I'm running the new unit through the test in Normal mode as well, I'll have updated results there by the end of the weekend. Given the rush to get the initial review out, you can expect a followup (along with a video review) sometime next week. I'll be working on it as well as some HDD/SSD caching stuff all weekend.
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  • MonkeyPaw - Friday, December 2, 2011 - link

    Sounds like Apple's wireless devices are displaying some anti-competative behavior! ;)
  • ol1bit - Sunday, December 4, 2011 - link

    I Love it!
  • TGressus - Friday, December 2, 2011 - link

    "As to why performance was lower with the Apple APs active, I'm not entirely sure. Chasing down RF interference issues can be a severe undertaking. One thing is for sure, the Prime is going to be far more finicky than its predecessor when it comes to reaching peak speeds over WiFi."

    That's one theory, I suppose...

    I'd never use "just works" networking infrastructure tho, so maybe I'm biased.
  • Anand Lal Shimpi - Friday, December 2, 2011 - link

    The second part of that statement has to do with the fact that the TF Prime's WiFi performance is far more sensitive to orientation to the AP when compared to the original Transformer.

    Take care,
  • UpSpin - Friday, December 2, 2011 - link

    Anandtech is really one of the most reliable tech sites right now. I'm really appreciating your honesty regarding your readers and especially your effort to do the best possible.
    This review is such an example, you did a review in time, just like every other tech site, but you were honest that you had not enough time, like all the other tech sites hadn't too but haven't mentioned it. Unlike you, they just posted a poor review and left it that way. You instead did the best with the limited time you had and even after you wrote the initial review try to do a review worth such a new device, and find how it really performs.
  • Anand Lal Shimpi - Friday, December 2, 2011 - link

    Your support really is appreciated, we do this stuff out of love and it really helps to have such awesome, honest and thoughtful readers. You guys keep us honest and you keep us motivated :)

    Take care,
  • eddman - Friday, December 2, 2011 - link

    I can't thank you enough for all the hard work you're doing. Truly, you and anandtech's writers are without rival. Most other websites and blogs just do a quick review and if there is a problem with the device, they simply bash it and the brand instead of looking for the root of the problem.

    I really appreciate your detective work, how you look for possible causes and how you contact the companies and try to work with them to solve things or to get an official response. Your honesty and devotion towards your work is very special.
  • jesh462 - Sunday, December 4, 2011 - link

    Me too! I enjoy reading your articles even if it's on gear that I never intend on purchasing for this reason.
  • MrSpadge - Friday, December 2, 2011 - link

  • BigLan - Friday, December 2, 2011 - link

    So Asus sent you a cherry-picked review unit which still has wifi issues, but also have remarkable battery life? I think I'll wait for reviews on actual retail units before making my mind up about this tablet.

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