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With the Lumia 640, Microsoft has held true to one of the proudest traditions of the 600 range: a healthy processor. Purring away under the hood of the polycarbonate slab is a quad-core Qualcomm Snapdragon 400 processor, clocked at 1.2 GHz. This is the very same processor found in the Moto G (2013), and as such is a tried and true performer.
I found that swiping around the OS was a pleasant experience. The usability of Windows Phone at the lower end of the price spectrum has often been touted as excellent. Approximately 50% of this general impression is based in reality – in my experience the operating system masks app loading times with myriad animations.
As such, it is a pleasure to say that, on the Microsoft Lumia 640, I did not find this to be the case. The best test of OS responsiveness is a measure of the 'app rehydration', or app refresh times when multi-tasking.
When loading apps such as Spotify from sleep, there was functionally no delay, whereas on a device such as the Nokia Lumia 540, this could easily be upwards of five seconds. The Lumia 640 is a scorcher, at least when swiping around.
Happily, this general level of performance continued into gaming performance. Whatever I threw at it, the device mostly took it in its stride. Games such as Subway Surfers, Sparkle 2 and Timberman ran without a hitch.
Though Windows Phone has often lagged behind in the processor department when compared to supercharged Android phones such as the Samsung Galaxy S6 and the HTC One M9, at least in the budget range Microsoft appears keen to catch up.
Battery life
To put it simply, the battery life of the Microsoft Lumia 640 is excellent.
With a relatively low-resolution display, a power-sipping processor and the efficient Windows Phone OS, the ingredients were all there for the success of the Lumia 640.
When matched with a large 2500mAh unit, all of these factors virtually guarantee that the device will last comfortably through a long day of work and play.
Unplugging the device at around 7:30am, listening to a few hours of Spotify, catching up with a few shows on BBC iPlayer Radio, browsing the internet for around an hour on HSDPA+ and whiling away dull moments with a little gaming saw the battery drop to around 45% by 6pm.
Leaving the device unplugged throughout the night, I saw a further 2% drop, leaving ample charge for the next day.
In all, regardless of your use case, this device has great battery life. And, as a bonus for those who travel frequently, and power users, it is removable, allowing for 'hot-swapping' a new unit in to top things up.
To help last through the day, Windows Phone comes bundled with a battery saver app, which comes with a powerful power-saving option. When activated, this allows background tasks to be shut down completely, except for whatever app is being used directly, limiting connectivity significantly, but proving useful in a pinch.
For me, activating this option dependably added around two to three hours to battery time. Typically, this gave an estimated 28 hours of power, and with power saver it increased to 31. Though it doesn't include any fancy greyscale power-saving options, as found on the Samsung Galaxy S6, this is a dependable and practical alternative.
Overall, I was very pleased with the battery life of the Microsoft Lumia 640 LTE. I came to the device with high expectations, given its screen, processor and the size of its battery unit, and yet was pleasantly surprised.
