The Apple MacBook Pro 13in is a glorious laptop. It’s thin and light, gorgeous both to look at and to use, and it packs no small amount of power in its tiny chassis. Yet our tests have uncovered a performance issue that will affect every user.

We ran our new Real World Benchmarks on the top-end model, with a dual-core 2.7GHz Intel Core i7-2620M processor, 4GB of DDR3 and a 500GB hard disk. It’s a very fast laptop for its size, as a final score of 0.70 shows – that’s only around 20% slower than the top-end quad-core 17in model. Yet it’s not quite as fast as it should be.

We first noticed a problem when the benchmarks finished five full runs and the results popped up on screen: the times taken to complete several of the most intensive tests were rising with each run. This would suggest an overheating problem, so we ran a temperature monitor to find out how hot this Sandy Bridge CPU was getting. Here are the readings both when idle and under full load:

We should point out that 93°C is not necessarily too high for a modern CPU, but it is the root cause of the bigger performance problem. To explain, here’s that full-load temperature again, along with Intel’s own Turbo Boost monitor:

The temperature of 93°C was reached with the processor peaking at 2.7GHz. The Core i7-2620M should be able to Turbo Boost up to a maximum of 3.4GHz, but in this laptop it doesn’t top 2.7GHz at any temperature.

For comparison, here is the same reading from the Core i7-2720QM in the top-end 17in model:

Here it’s being Turbo Boosted from its stock 2.2GHz. Notice how the blisteringly fast 17in model only peaks a few degrees hotter than the 13in, and that’s with the maximum boost. As soon as the fans kicked in that settled comfortably in the high eighties.

What does this all mean? Well, if the CPU in the MacBook Pro 13in hits 93°C at stock speeds, we can only imagine how hot it would get if Turbo Boost was allowed to kick in. So we suspect Apple has disabled it completely to prevent overheating in such a tiny chassis.

It’s an issue we haven’t seen highlighted, perhaps because to the end user it doesn’t really affect the day-to-day experience – and it shouldn’t put you off buying what is in every other way a fantastic piece of kit. But Apple is promoting this on its website as a Turbo Boost-enabled laptop. We’ve asked Apple for comment and await its response.

We also now have the £999 model with its 2.3GHz Core i5 processor in the Labs. We ran the same tests on that one and can confirm that its processor is Turbo Boosting in Boot Camp as it should. The issue is unique to the i7 model.

However, secondly, we must doff our caps to Anandtech and show you our reading from a utility they used called MSR Tools:

We stand corrected on one count: it is indeed Turbo Boosting in OS X. We ran a temperature monitor for several minutes as well, and those boosted speeds occurred with a peak temperature of 93°C, the exact same as the peak in Windows without the boost.

The Turbo Boost issue therefore looks to be one of processor cooling in Windows. That affects a far smaller group of users that an OS X flaw, but it remains a mystery: does the Core i7 model of the MacBook Pro 13in run so hot under Windows drivers that Apple has chosen to disable Turbo Boost? Our tests make that a plausible scenario.

Heat is an issue that’s difficult to ignore. Even on the Core i5 model, just unpacking a large zip file had the Turbo Boosted Core i5 quickly rising to 90°C; during a stress test that hit 99°C. And that has a knock-on effect: with an IR temperature gun we measured the aluminium underside of the laptop at a thigh-scalding 60°C!

We’re more sure than ever that Apple had a real task on its hands getting such fast processors into this chassis, and from everything we’ve seen we’re leaning away from the top-end 13in model as a purchase. If the sight of our benchmarks gradually getting slower with each consecutive run wasn’t enough to highlight the cooling problem, a heat gun pointed at the metal underside certainly was.

There is one plus to the Turbo Boost mystery, however: if you intended to buy a MacBook Pro 13in and install Windows on it, you’ll probably find the cheaper model actually runs faster than the top-end one. Save yourself £300.

According to the Apple website, an upgrade from 4GB to 8GB of RAM will cost no less than £839.99. That’s over £200 a gigabyte (my mother always said the A-Level maths would come in handy).

For that money you could buy five of the original Eee PC 701s from Technoworld.com and still have over £50 to spare. 

What’s more, Crucial is selling a near identical 2 x 4GB 1066MHz DDR3 kit for £469 – about £370 less than Apple. That’s quite some mark-up, even by Apple’s standards. 

(Thanks to PC Pro forum member big_D for the tip off).

The first thing that strikes you about the machine is its incredible build quality. Jobs made much of Apple’s new manufacturing process – pioneered with the MacBook Air – where the main part of the chassis is hewn from a single block of aluminium, and it certainly makes for a very robust-feeling machine. The original Pro was no pansy in this regard, but if that was solid as a rock this is positively granite.

Try to twist the base and you’ll meet firm resistance. Try to flex the lid and there’s no give at all, no showthrough, nada. No matter how hard we pressed we failed to produce the merest hint of a ripple.

The other big news is the huge glass multitouch trackpad. This measures 5in from corner to corner, but the size is only part of the story. There’s no longer a button below it; instead the entire trackpad is clickable. This is no standard tap-to-click pad, though – it’s mechanical. Push it down and after a millimetre or so, it clicks. Time will tell how intuitive this is – it certainly feels a bit weird at first – but it gets around the accidental cursor activation that plagues so many Windows-based machines.

The other part of the trackpad story is that a few new gestures have been introduced. You can now perform a ‘four fingered swipe’ up, down, left and right to activate various features. Placing four fingers on the pad and pulling down clears the screen; swiping them back up, puts your application windows back where they were.

And Apple has now introduced a way of activating the context menu without having to use a keyboard shortcut. A two-fingered tap pops up the context menu, or zones can be set up at the bottom right or left of the trackpad to do the same job.

Apple has ditched the traditional silver-coloured keyboard in favour of trendy, black scrabble tiles, which looks odd, but it feels perfectly pleasant to use. And the screen looks good, too – a 15.4in widescreen with a 1,440 x 900 pixel native resolution and LED backlight, with a glossy glass front that stretches right out to the edges of the lid.

There’s dual graphics here, in the shape of Nvidia’s 9400M integrated graphics and its 9600M GT discreet chipset – you can switch between the two depending on whether you want high performance or longer battery life. And, in an interesting departure for Apple, you can now access the hard drive and battery by removing just the one cover.

Elsewhere, typical Apple design touches abound: the battery gauge has moved from the bottom of the case to the side, so you can see what your battery level is at a glance; there’s an ambient light sensor to dim the screen and light up the keyboard.

All in all, it’s a very luxurious-feeling machine. To see if it stacks up in the performance or value stakes, though, you’ll have to wait for our full review later in the week.

The raw specifications, just to recap are as follows, with two models available initialy: 2.4GHz or 2.53GHz Intel Core 2 Duo processors, 2GB or 4GB of RAM, 250GB or 320GB hard disks (SSDs optional), DVD writer (no Blu-ray), Nvidia 9400M / 9600M GT dual graphics with either 256MB or 512MB of dedicated graphics memory, Gigabit Ethernet, FireWire 800, Mini DisplayPort, 2 x USB, ExpressCard/34, Mac OS X