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Real-World Performance And Battery Life

Apple's iPad 2 Review: Tom's Goes Down The Tablet Rabbit Hole
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Real-World Benchmarks

Early on we discovered how difficult it is to benchmark tablets.

Apple iPad: Input Lag Benchmark

Benchmarking responsiveness with a camera is the fastest approach. Of course, normal cameras won't cut it, since they only shoot at 29 FPS. That's unacceptable if you're trying to measure precise time differences. Going the stop-watch route is no better due to human-introduced errors. That's why I'm using a 1000 FPS high-speed camera to measure performance. Since, 1 frame = 1 millisecond, it’s possible to measure timings with a high degree of accuracy.

Tom's Hardware's Real-World Benchmarks
High Speed Camera
Startup Time
(Cold Boot)
Input Lag
Launch Safari
iPad
31.359 sec
290 millisec
717 millisec
iPad 2
25.977 sec
235 millisec
676 millisec


Input lag is time it takes from pressing a key to the time it takes for it to appear as text on the screen. This tells you how fast the iPad is registering an action. Ideally you want low input lag so that you don't feel the tablet stuttering as you type or click on buttons.

Apple's original iPad has an input lag close to 300 milliseconds, which is noticeable if you have a tendency to type fast. According to research published by Clemson University, the average college student has a reaction time of 200 milliseconds to visual stimuli. The difference between 290 and 200 milliseconds is what you can actually "feel." If you type quickly, consider a 90 millisecond delay adding up per keystroke. Just Google "input lag iPad," and you'll see the how much of a pain this can be.

The iPad 2 has a more favorable result of 235 milliseconds, which means that input lag is nearly unnoticeable.

Battery Life

Testing a tablet’s battery life tends to be highly variable unless you control the entire experience from beginning to end. Cumulatively, touch gestures don’t have a great impact on battery life. The biggest factors are CPU/GPU processing, screen brightness, volume, and WiFi use. In order to accurately measure battery life, I coded a script that automatically plays MP3s at 50% volume while browsing different Wikipedia pages every 12 minutes. This benchmark is probably overkill, but it gives you an idea of a worse-case scenario.

Battery Life
Maximum Brightness, Dynamic Brightness Disabled, 50% Volume
HH:MM
WiFi + MP3
WiFi Off
H.264 Playback
iPad
5:36
8:01
iPad 2
5:55
8:57


Based on the iFixit iPad 2 teardown, Apple's using the same battery in the iPad 2, so the improved battery life has more to do with efficient hardware.

Recharge Time

Recharge Time
AC Adapter
HH:MM
to 90%
to 100%
iPad
3:29
3:52
iPad 2
3:01
4:02


Charging times are a double-edged sword. Ideally, you want a nice slow charge so that your battery lasts more than a few hundred cycles. Fast charge times keep you away from the wall socket longer, but in the long run they also cut down on the battery's health. Usually, the rate of charge starts to slow down somewhere in the 80% to 95% region, which is why the charging time from 0% to 10% is faster than 90% to 100%. This is where the iPad 2 shows its strength. It gets to 90% faster, but it eases up on the charging current above 90% to keep the battery healthy.

Recharge Time
USB Adapter
HH:MM
to 90%
to 100%
iPad
6:38
7:25
iPad 2
6:23
7:24

If you're charging an iPad through a computer's USB port, expect to wait about 7 to 8 hours for a full charge.

Wireless Performance

It's wrong to look only at throughput to get a sense of network speed. Yes, the iPad 2 does slightly worse in throughput, but there are other factors that affect wireless performance.  Latency, processing time, and the type of data being sent also effect the perceived "fastness" of a network connection.

Think of a phone call. Throughput is the audio quality. Latency is the amount of time from when you speak into the phone until the person on the other side hears you. And processing time is your brain mulling what the conversation itself. If we apply this to networking, throughput is the amount of data you can send over time, latency is the lag due to data transmission, while processing time is the overhead incurred by receiving the data.

Now consider that latency plus processing time equals response time. This is where the iPad 2 holds a clear advantage. Apple didn't change the 802.11a/b/g WiFi + Bluetooth 2.1 controller (Broadcom's BCM4329), but the A5's horsepower is significant enough that it reduces latency and processing time. So even if the throughput isn't great, the iPad 2 holds a commanding lead in response time that helps it load Web pages and download emails faster over WiFi.

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  • 3 Hide
    Yuka , June 16, 2011 4:46 AM
    What about adding other tablets in the mix?

    The XOOM could be a good choice, or the Asus Transformer.

    Cheers!
  • 7 Hide
    acku , June 16, 2011 4:49 AM
    We'll get to the others soon enough, but it's difficult to talk about other tablets without talking about Apple products.

    Cheers,
    Andrew Ku
    TomsHardware.com
  • 0 Hide
    Nintendork , June 16, 2011 5:15 AM
    Samsung Galaxy 10.1 anyday.
  • -6 Hide
    gidgiddonihah , June 16, 2011 5:24 AM
    Here is the article where all the Apple fanboys start to tear this article up :) .
  • 3 Hide
    gidgiddonihah , June 16, 2011 5:27 AM
    Oops, sorry for the poor grammer :) . Posted without rereading...

    Here is an article that Apple fanboys would be glad to rip up.
  • 2 Hide
    Tijok , June 16, 2011 5:37 AM
    gidgiddonihahHere is the article where all the Apple fanboys start to tear up .


    Fixed it for you. ;) 
  • 1 Hide
    Benihana , June 16, 2011 5:55 AM
    Still no HDD expandability? No thanks. I'm not rich.
  • 2 Hide
    Anonymous , June 16, 2011 6:36 AM
    Disagree.
    Like most computer guys like myself, adding an ipad won't make us to pack our PC/Mac to our closet. But again, mistakes like Microsoft or Linux, the "most computer guys on earth" are actually just a small group in total.
    For example:
    i've been teaching my 80 years old grandma to use pc to download, install and play simple games for years, no success. then she learned how to find/download/install/play many games after few days playing with my ipad.
    my 5 years nephew reads/plays/watch cartoons all on ipad now, she didn't turn on her pc for weeks.
    For myself, i uninstalled all my online video, movie client applications from my laptop, as I found watching these on ipad is much comfortable.

    Yes I still do my works on my pc, mostly in my office. At home, now the only thing force me to turn on my pc is to play world of warcraft
    I mean, who says ipad can't replace anything?
  • 3 Hide
    acku , June 16, 2011 7:33 AM
    joeyluDisagree.Like most computer guys like myself, adding an ipad won't make us to pack our PC/Mac to our closet. But again, mistakes like Microsoft or Linux, the "most computer guys on earth" are actually just a small group in total.For example:i've been teaching my 80 years old grandma to use pc to download, install and play simple games for years, no success. then she learned how to find/download/install/play many games after few days playing with my ipad.my 5 years nephew reads/plays/watch cartoons all on ipad now, she didn't turn on her pc for weeks.For myself, i uninstalled all my online video, movie client applications from my laptop, as I found watching these on ipad is much comfortable. Yes I still do my works on my pc, mostly in my office. At home, now the only thing force me to turn on my pc is to play world of warcraftI mean, who says ipad can't replace anything?


    I'd actually argue that in your case you're not replacing a PC, you're augmenting it. Granted, there will be others like your nephew and grandmother who can use an iPad as their primary device.
  • 8 Hide
    damianrobertjones , June 16, 2011 7:45 AM
    May I simply say, "thank you" to Toms for writing a well thought out objective, honest and practical review of thr iPad2. Instead of getting carried away you've hit the nail on the head.

    P.s. I use an Acer W500 and I still struggle to justify why i have it.
  • 5 Hide
    Maziar , June 16, 2011 9:19 AM
    Good too see you guys are writing about tablets.Hope this trend continues and we can see reviews of more tablets :) 
  • 2 Hide
    Marcus52 , June 16, 2011 9:45 AM
    In my opinion, the tablet is a fad that will go away when everyone finds out they are very cool looking toys that really don't add anything to what you can do.

    Oh, don't get me wrong; I think they'll make their permanent mark on the smart phone and laptop scenes, the devices that really fit into people's lives - but the tablet is too limited and too clumsy in actual use.

    Certainly, they have their niche uses - as book readers, like the Kindle, for example, but as something that will actually replace anything, I think not. Lots of coolz, little practicality.

    ;) 
  • 2 Hide
    VVV850 , June 16, 2011 9:59 AM
    What about light bleeding? I mean, the number of Ipads 2 that have this issue is staggering and has to be included in a review
  • 2 Hide
    molo9000 , June 16, 2011 10:33 AM
    Marcus52In my opinion, the tablet is a fad that will go away when everyone finds out they are very cool looking toys that really don't add anything to what you can do.Oh, don't get me wrong; I think they'll make their permanent mark on the smart phone and laptop scenes, the devices that really fit into people's lives - but the tablet is too limited and too clumsy in actual use.Certainly, they have their niche uses - as book readers, like the Kindle, for example, but as something that will actually replace anything, I think not. Lots of coolz, little practicality.

    They don't "add anything to what you can do", but they do certain things much better than other devices.

    Reading this article on my iPad while sitting on a sofa was certainly much more comfortable than reading it on my desktop or laptop.
  • 0 Hide
    phraun , June 16, 2011 11:07 AM
    molo9000They don't "add anything to what you can do", but they do certain things much better than other devices.Reading this article on my iPad while sitting on a sofa was certainly much more comfortable than reading it on my desktop or laptop.


    You need a more comfortable computer chair. =)
  • 4 Hide
    damianrobertjones , June 16, 2011 11:07 AM
    Reading this article on a 108" projector screen was a lot more comfortable... :) 
  • -1 Hide
    altoidman85 , June 16, 2011 11:14 AM
    molo9000They don't "add anything to what you can do", but they do certain things much better than other devices.Reading this article on my iPad while sitting on a sofa was certainly much more comfortable than reading it on my desktop or laptop.


    You should have taken the money you spent on your ipad and bought a more comfortable desk and chair for your desktop. Then a few cases of beer.
  • 1 Hide
    brendonmc , June 16, 2011 11:48 AM
    Spot on. Even Microsoft recognized that Windows Mobile applications had to be compatible with the full versions. Unfortunately there just wasn't the hardware to make it run....well....
    Oh, and using a stylus to type sucks.

  • -4 Hide
    jdamon113 , June 16, 2011 12:05 PM
    This is Boring, just like a tablet.
  • 2 Hide
    Anonymous , June 16, 2011 12:27 PM
    I only justify having a tablet for my girlfriend, who's work place (Hospital ER) will not allow laptop use during her down time, to browse or chat w/ me. But they do allow them to read books, or e-readers, so she has a nook color running Cyanogenmod7, so i guess the onl ytime a tablet is useful to us is when a laptop strictly isnt allowed.
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