Lenovo ThinkPad X1 Carbon (2015) Review: Back To Basics With Broadwell


SunSpider and Lame MT

In our custom LAME MT MP3 encoding test, we convert a large WAV file to the MP3 format, which is a popular scenario that many end users work with on a day-to-day basis to provide portability and storage of their digital audio content. LAME is an open-source MP3 audio encoder that is used widely in a multitude of third party applications.

Lame MT Benchmark
Audio Transcoding on the CPU
For this test, we created our own 223MB WAV file (a mile-long Grateful Dead jam) and converted it to the MP3 format using the multi-thread capable LAME MT application, in both single and multi-thread modes. Processing times are recorded below, listed in seconds. Shorter times equate to better performance.

LameMT

Here the 2015 ThinkPad X1 Carbon puts up the best score we've ever recorded for an ultrabook class machine and once again distances itself from last year's model.

SunSpider 
Javascript Processing Test (CPU)
The Webkit Open Source Project suggest the following about the SunSpider Javascript benchmark...

Unlike many widely available JavaScript benchmarks, this test is:

Real World - This test mostly avoids microbenchmarks, and tries to focus on the kinds of actual problems developers solve with JavaScript today, and the problems they may want to tackle in the future as the language gets faster. This includes tests to generate a tagcloud from JSON input, a 3D raytracer, cryptography tests, code decompression, and many more examples.

Balanced - This test is balanced between different areas of the language and different types of code. It's not all math, all string processing, or all timing simple loops. In addition to having tests in many categories, the individual tests were balanced to take similar amounts of time on currently shipping versions of popular browsers.

Statistically Sound - One of the challenges of benchmarking is knowing how much noise you have in your measurements. This benchmark runs each test multiple times and determines an error range (technically, a 95% confidence interval).

SunSpider

In SunSpider, the X1 Carbon also shows strong by just missed the top slot by a few milliseconds versus the highly optimized Surface Pro 3 convertible. The delta is also negligible of course and once again, Lenovo's new machine puts up excellent numbers.

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