You may have experienced the situation where you have a desktop and laptop with what appears to be the exact same hardware, yet the laptop is notably slower – so much so that you really notice it. It doesn’t matter if it’s Windows or Mac OS X, because when you’re on a laptop, you notice the slowness.
But why is it slower?
That’s what this article will answer for you.
Mobile CPU
The mobile CPU is always slower because it designed to emit less heat. CPUs, as you know, run hot. They all do. Heat is a huge enemy for laptops because it eats up battery life quickly an also can potentially set the laptop chassis on fire – literally. As such, mobile CPUs are designed to be smaller and run cooler. The tradeoff to this is that they are notably slower compared to a full-size desktop processor.
When you see “Core i3″ and “Core i3 mobile”, they may have the exact same GHz speed rating, but the mobile processor will always be slower.
2.5-inch hard drives
The vast majority of laptops today use 2.5-inch platter-based hard disk drives, abbreviated HDD for short. This is the same type of storage technology we’ve been using for decades, but in a smaller form factor. A desktop hard drive is 3.5-inch.
What makes a 2.5-inch laptop HDD slow is the fact they run at 5400 RPM while a standard 3.5-inch desktop HDD runs at 7200 RPM.
The HDD is without any doubt the biggest bottleneck on a laptop – more so than the CPU. The 5400 RPM speed is purposely engineered that way to once again defeat the heat. Slower spins = the less heat the HDD will emit.
5400 is so slow that even if you decided to opt for a better CPU in the purchase of a laptop, the HDD 5400 speed will still cause a lot of slow load times for any program you use.
Currently there is Solid State Disk, abbreviated SSD for short. It is the next generation of storage media and has no moving parts, therefore it greatly outperforms HDDs in every way – however at present they’re still far too expensive. For example, a 32GB (yes, just 32GB) SSD will cost you $80. Something more reasonable like a 128GB will cost you $200.
Prices for SSD will drop dramatically when 2011 comes around.
It should also be noted that Windows XP has a horrible time “dealing” with SSD. If running Windows, it’s required to use Windows 7 in order for the Windows OS to operate properly on SSD.
When SSD becomes more affordable, laptops will become speed monsters and easily overcome all limitations of the HDD and the slowness of mobile CPUs.
Shared video memory
Last but certainly not least on the list of things that make a laptop slow is the fact very few have dedicated video memory. What’s used instead is shared memory. For most applications it’s passable, but it’s also what keeps you from doing “heavy” video-intensive things like HD video editing and some higher-powered video games.
You can order a laptop with a dedicated graphics card, but it will cost you plenty. Usually it adds about $50 to $100 to the price of a laptop just to have one.
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edwartr
922 days ago
Overall, I totally agree with your article. You hit the nail on the head with most of the reasons that laptops are generally slower than desktops with the same hardware.
However, you seem to suggest that all 2.5 inch ‘laptop’ hard drives are 5400 rpm and that all 3.5 inch ‘desktop’ drives are 7200 rpm. In fact, you can go down to your local Best Buy and pick up a 7200 rpm 2.5 inch SATA notebook hard drive in multiple sizes; and for not that much more (usually 10% to 20% more)than the same sized 5400 rpm drives. Also, all of these “green” 3.5 inch desktop drives that are being sold like crazy for cheap prices are all 5400 or 5900 rpm. I have been seeing more and more normal desktop systems coming with 5400 or 5900 rpm drives as their only 3.5 inch hard drive. Now, it is hard to find a laptop in the store that comes with a 7200; but you can easily get one if you are ordering from Dell, HP, etc. online; though they can add a bit more price than if you got the drive yourself.
Some hard drive companies are still shipping/packaging their drives with basic cloning/imaging software and you can easily use this to image over your old 5400 rpm drive to a new 7200 drive though you will need a USB to SATA adapter so that you can have both drives hooked up at the same time to allow imaging. However, such an adapter is cheap and the process is very easy. And that it is all extra cost in buying the 7200 HDD in addition to the one already in your laptop; but if your current drive is too small or having issues, this can not only allow you to get much more hard drive space but also a speed increase on an older laptop. I have done this for more than a few of my clients.
Now, I will also state that going to a 7200 rpm notebook drive will raise the heat output of your laptop. If you use good cooling practices (a good cool tray or at least keep good, open airflow around the laptop) then you should have no issues; but it is something to remember. And with all modern processors, if they start to get too hot, then they will start clocking themselves back (slowing their processing speed) until they reach a level that they can handle the heat. This will also slow your laptop down. If your laptop HDD is giving off too much heat, it could overload your processor’s heatsink/fan and cause this clock back which would negate most of your speed increase using the faster HDD.
SSDs are great being cooler and faster; but you are correct that they are still too expensive and don’t work as well with XP as they do Windows 7.
Shared Video Memory is an issue but getting better. With both Intel’s and AMD’s move to integrate the GPU on the CPU, the speed of integrated GPUs is increasing a lot. And AMD’s ATI gpus are definitely good performers so that will help. Having / setting the integrated video to use a decent amount of RAM helps performance a bit now though you have to weigh the cost of lowering the amount of RAM available for the rest of the system. Sometimes, it is worth raising the RAM on the whole system to allow a decent amount for the integrated GPU and the rest of the system.
Rich Menga
922 days ago
I will quote myself here, “The vast majority of laptops today use 2.5-inch platter-based hard disk drives” and “..a standard 3.5-inch desktop HDD runs at 7200 RPM.”
What you’re talking about are, for lack of a better term, “special edition” hard drives.
Placing a 2.5-inch 7200 RPM HDD in a laptop originally designed for a 5400 (which most are) is a seriously bad idea. You run the risk of literally melting the chassis and/or literally setting your laptop on fire.
I also want to make this very clear: No “good cooling practices” will prevent a laptop chassis from physically getting damaged from heat of a 7200 RPM 2.5-inch HDD if the original was a 5400. The chassis was not designed for an HDD that outputs that kind of heat, and replacing a 5400 with 7200 is a seriously stupid idea, because even with the best possible laptop stand with fans blowing under the laptop 24/7, THE CHASSIS WILL STILL MELT or IGNITE. It will happen. The CPU will not have enough time to “scale itself back” because by the time it does, the chassis has already started to melt and you will have a catastrophic cascade failure – smoke and all.
If you’re thinking, “The heat output isn’t that much higher..”, yes it is. Consider the chassis it’s going into.
I cannot state this any more strongly: DO NOT replace a 2.5-inch 5400 in a laptop with a 7200. Just don’t do it. You WILL have issues, as in a dead and literally burnt laptop. Saying otherwise is seriously bad advice.
For a 3.5-inch desktop HDD there is 5400, 7200 and 15000 widely available. The most reliable is the 7200 and always has been.
The 5400 RPM 3.5-inch HDD is a marketing ploy and nothing more. “Use X, it spins less and uses less power therefore better for the environment.” Yes, it does use less power but at the expense of access time – and a lot of it.
The 15000 RPM drive can be used in a desktop because you can cool it direct-on-drive (whereas in a laptop you cannot). It’s faster yet has a higher failure rate.
Derek
843 days ago
I have tried two SSD drives (both 128) the first was a Crucial. The second was a OCZ (sorry don’t have them here or I’d put the model numbers). I did notice amazing speed at first but after a few months of use I started getting some issues with lag that seemed to be getting worse and worse. Reloading fixed the issue. I seem to recall reading somewhere that this happens sometimes.
I finally put a 500GB 7200 Seagate in and imaged over the drive and its been running flawlessly for the last 4 months. Interestingly enough, the PC Rating didn’t change between any of the 3 drives with the hard drive being the lowest rating at 5.1 each time. I’m rocking a Dell E6510 / 8 GB RAM, Windows 7 Ent x64 / standard OS setup following Dell’s guide on installing the OS.
Please note that I didn’t run any benchmark tools; this was all my perception…YMMV.
Bruce H. Johnson
843 days ago
Yeah, I’ve got plenty of experience running laptops, both personal ones and those at my company. — About 30+ years.
Probably a combination of “mobile” CPUs, memory and HDD speed. The laptops have almost always been slower than a similar desktop/tower.
At the office, I always spec out a “cheap” desktop on sale at Fry’s if we’re going to squat at a client’s site.
I’ve only had 2 desktop (3.5″) HDDs go bad on me in thousands of hours of operations. I’ve had 3 laptop HDD which needed replacement and another sitting on the floor next to me now.
Those are based upon maybe 50% or fewer hours than the equivelent desktops.
The three laptop HDDs needed the original mfr to replace the drives; we could never trust a third-party (at least so far) vendor to get the interface electrical and mechanical correct.
The nice part about desktops is that you can almost always drop in a bigger and faster HDD (or add it) with no sweat about heat or power. I’ve replaced PATA and SATA and earlier drives with no problems — that’s because I’ve had 95% of any data already backed up.
Yeah, use the laptops if you really need the portability or can’t really afford at desktop. Otherwise, we can now buy a top-of-the-line, easily-upgradeable desktop at 1/3 or 1/2 the cost of a laptop. Totally depends on your circumstances.