Slow JavaScript performance in Microsoft Surface RT

Outlook Web Access is useful on Microsoft’s Surface RT, since the built-in mail client is only basic. However I noticed sluggish performance, which made me wonder if Microsoft’s “Chakra” JavaScript engine is slow on Windows RT.

I ran the Sunspider JavaScript performance test on the Samsung Slate 7 I bought back in February, which has a 1.6Ghz Core i5, and compared it to the same test on Surface RT, which has a 1.3 Ghz NVidia Tegra 3 chipset.

The Samsung slate was 5.11 times as fast. Question: how much of that is down to the Core i5 being a faster CPU, and how much is down to a less well optimized Chakra engine?


Incidentally, the Apple iPad 2 which has an Apple A5 processors running at around 890 Mhz is approximately 33% slower on the SunSpider test. Since the CPU is clocked 45% slower that is a good result for the iPad 2 and Safari.

A Google Nexus 7 on the other hand which has the same Tegra 3 chipset as the Surface is about 55% slower than the Surface, which is poor.

3 thoughts on “Slow JavaScript performance in Microsoft Surface RT”

  1. It’s likely that JIT (Just-in-Time) compilation of js is disabled, maybe they haven’t done the ARM code for doing. Another less likely possibility is MS actually enforcing the same restrictions other programs have on the RT platform by not allowing executable memory. This is highly unlikely, so an update with probably have JIT for ARM and fix the performance.

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