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Windows Phone Performance – Part 8 of many: Lumia 620 performance

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In this post, I’ll take a look at the performance of the Nokia Lumia 620 from a developer’s point of view. This post is part of my Windows Phone Performance series.

HUGE thanks to Joost von Schaik for performing the tests in this article. Since I don’t have access to a Lumia 620, without him, this post would not have been possible.

The Nokia Lumia 620

image The 620 is the almost-smallest member of Nokia’s Windows Phone 8 family yet. The 520 is smaller, but not yet available. The 620 is a great phone, and provides a good Windows Phone 8 experience for a fraction of the price of its bigger brothers, such as the 820 and the 920 (both of which we have tested earlier).

The 620 has a dual core Snapdragon S4 processor. This is not the same as the ones found in the 920 (MSM8960T) and the 820 (MSM8960) though (both of which run at 1.5GHz). The 620 has an MSM8227, running at 1 GHz, and an Adreno 305 GPU. The screen has 800x480 pixels (same as the 820, but lower than the 920). Another notable difference is that the 620 has 512 MBytes of RAM onboard. While this may affect multitasking and other end-user features, our tests were not impacted by the lower amount of memory.

Because of its low price and attractive design, the 620 is expected to sell very well in countries such as India, Chine and Eastern Europe (just like the 610 did).

Application Loading / CPU Performance

For this test, I am using the same test I used for the other phones, from the second part of this series: It’s Full of Stars!

Number of Stars Lumia 620 Optimus 7 Lumia 800 Lumia 920 Lumia 820
100 310 399 347 164 497
1000 727 1133 846 449 539
2000 1119 1882 1357 711 723
5000 2425 4258 3007 1557 1465
10000 4569 8348 5792 2913 2899
15000 6887 12183 9057 4404 4349
20000 9206   11646 5903 5774
25000 11205     7328 7283
30000 13235     8861 8756
35000 15546     10314 10131
40000 17929     11677 11589

image

We get the expected result – the CPU clock difference between the other WP8 phones (920 and 820) clearly means slower startup and computational times. In fact, if we compensate for the CPU clock, the numbers are pretty much exactly the same. The 620 has no problem beating second generation Windows Phone 7 devices (such as the Lumia 800). The 800 has a single-core and outdated CPU, but runs at a 40% higher speed of 1.4 GHz. If we compare the 620 to the first generation WP7 devices, such as the LG Optimus 7, we get almost 100% performance gain. Moore’s Law in action here…

GPU Performance

To measure the raw CPU performance, once again I used the “Fill Rate Test Sample” from the MSDN article Performance Considerations in Applications for Windows Phone. This test turned out some surprising results!

Here are the numbers in table and chart format:

Rectangles Fill Rate Lumia 620 FPS Lumia 800 FPS Optimus 7 FPS Lumia 920 FPS Lumia 820 FPS
0 0 60 59 50 59 59
1 1.03 60 59 50 59 59
5 1.53 60 59 50 59 59
10 2.15 60 59 50 59 59
15 2.78 60 59 48 59 59
20 3.47 60 59 38 59 59
25 4.02 60 59 34 59 59
30 4.65 60 59 30 59 59
35 5.28 60 59 26 55 59
40 5.9 60 59 23 50 59
45 6.53 60 59 21 45 59
50 7.15 60 59 19 42 59
55 7.78 60 53 17 40 59
60 8.4 60 49 16 36 59
65 0.03 60 45 15 33 59
70 9.65 60 43 14 31 59
75 10.28 60 42 14 30 59
80 10.9 60 40 13 29 59
85 11.53 60 37 12 26 59
90 12.15 58 34 11 25 57
95 12.775 53 33 11 24 54
100 13.4 49 32 10 23 51
105 14.03 45 30 10 22 48
110 14.65 44 30 9 21 47
120 15.9 40 27 9 20 44
130 17.15 40 26 8 18 41
140 18.4 40 24 7 17 39
150 19.65 36 23 7 16 36
170 22.15 33        
200 25.78 29        

image

Barring some measurement inaccuracies, the 620 performed just as good as our current champion, the 820 – even though the SoC runs at 66% speed! I’ve tried to find a reason for this difference, but I couldn’t find a definite answer. It seems like the bottleneck is elsewhere – perhaps the memory bandwidth, the graphics driver or some other architectural component. If you have an idea of why the 620 performs this much better than expected, please share it in the comments.

Nevertheless, it seems like developers we won’t have to worry about Fill Rates with the 620. It keeps an impressive 60 fps up until the Fill Rate of 12, which should be more than enough for any application. Even at a Fill Rate of 24, the frame rate is still above the red zone of 30.

Summary

From a developer’s point of view, the 620 is noticeably slower than the other WP8 devices when it comes to raw computing power. However, this speed difference shouldn’t cause much problems if you are sticking with the performance guidelines outlined in the previous parts of this series. Even better, when it comes to Fill Rate, you have nothing to worry about. For Fill Rate optimization, you should still use the Lumia 920. If you are also targeting WP7 devices, the Lumia 610 should be your baseline. The first generation phones are finally becoming rare enough to ignore minor FPS problems on. Which is good news, since it’s often extremely hard to keep the Fill Rate above their FPS drop point of 2.5.


Posted Mar 16 2013, 09:43 PM by vbandi

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