The Nokia Lumia 520 features a Qualcomm MSM8227 dual-core processor running a 1GHz and backed by 512MB of RAM.
Although looking a little dated on paper by now, it keeps the Windows Phone 8.1 operating system running smoothly during day-to-day usage. However, occasionally the loading times can get a little frustrating.
There's an Adreno 305 GPU on board that will handle 3D games downloaded from the Xbox section of the Windows Store with passable results.
The Nokia Lumia 520 comes with Wi-Fi and 3G as you'd expect and being a Windows Phone 8 handset your web browser choices are Internet Explorer and, er, Internet Explorer.
Still, it's optimised for HTML 5 and isn't the worst mobile browser we've ever used, so that's not the end of the world.
The 4-inch screen on the Nokia Lumia 520 is big and clear enough, so sites are fairly readable and images are reasonably sharp. However, if you're viewing a desktop site you might need to zoom in quite a long way.
The Wi-Fi and 3G performance could be better unfortunately. Using the TechRadar homepage as an example it took seven seconds to load the mobile version over Wi-Fi, which isn't bad but isn't exactly super-fast, while the desktop version took a whopping 24 seconds.
3G, as you can imagine, was even slower, exceeding 30 seconds for the desktop version of TechRadar.com.
Of course for under £100 you can't expect top-tier performance, and it's generally not too much of a problem if you stick to mobile sites. It's also roughly on a par with the performance of the more expensive Nokia Lumia 620 and the Huawei Ascend W1.
The Nokia Lumia 520 has a 1430mAh battery to keep it going. That's a slight boost over the 1300mAh battery found in the Nokia Lumia 620, but some way short of the 1950mAh battery packed into the Ascend W1.
The slight bump in battery size equated to a slight bump in performance over the Lumia 620, but it's an important improvement. While the Lumia 620 would sometimes struggle to make it through a day, the Lumia 520 generally seemed fine – though you'd still normally need to charge it overnight.
After TechRadar's patented battery test – running a 90-minute video from a fully charged handset with Wi-Fi on, social networks and emails set to push notifications and the screen turned up to full brightness – we saw the battery drop to 66% by the end.
That's not brilliant performance, but when used in other ways – for example phone calls, playing music, sending texts and so on, the Nokia Lumia 520 performed a lot better and unless you're watching a lot of videos you should easily get a day's use out of it.
The Lumia 530 has exactly the same 1430mAh battery as the Lumia 520, and in our battery benchmark test the Lumia 530's battery also dropped to 66%. This might not be surprising considering both handsets have the same battery, however it means that the newer Lumia 530 doesn't seem to benefit from any more energy efficient technology compared to its older brother.
Nokia rates the Lumia 520 for up to 360 hours of standby time over 3G, 14.8 hours of talk time over 3G, 9.6 hours of talk time over 2G or 61 hours of music playback, which sounds fair, though it notably doesn't post figures on video time.
If the battery doesn't live up to your expectations there is a battery saver, which prevents apps from syncing in the background. You can also invest in a spare battery, since it's easily removable if you just pop the back off the phone.
However if you'd rather not do that then the Huawei Ascend W1 might be a better bet, as that is one of the few Windows Phone 8 handsets to actually sport good battery life.