53
votes
1
answers
1K
views
What is the best way to set a register to zero in x86 assembly: xor, mov or and?
All the following instructions do the same thing: set %eax to zero. Which way is optimal (requiring fewest mac
64
votes
21
answers
383
views
Is inline assembly language slower than native C++ code?
I tried to compare the performance of inline assembly language and C++ code, so I wrote a function that add tw
56
votes
4
answers
3K
views
Why would introducing useless MOV instructions speed up a tight loop in x86_64 assembly?
Background: While optimizing some Pascal code with embedded assembly language, I noticed an unnecessary MOV i
49
votes
12
answers
1.4K
views
Is 'switch' faster than 'if'?
Is a switch statement actually faster than an if statement? I ran the code below on Visual Studio 2010's
63
votes
5
answers
1.7K
views
Why does Java switch on contiguous ints appear to run faster with added cases?
I am working on some Java code which needs to be highly optimized as it will run in hot functions that are inv
58
votes
11
answers
1.9K
views
Why does C++ code for testing the Collatz conjecture run faster than hand-written assembly?
I wrote these two solutions for Project Euler Q14, in assembly and in C++. They implement identical brute forc
64
votes
11
answers
1.9K
views
Replacing a 32-bit loop counter with 64-bit introduces crazy performance deviations with _mm_popcnt_u64 on Intel CPUs
I was looking for the fastest way to popcount large arrays of data. I encountered a very weird effect: Changin
62
votes
14
answers
663
views
Is < faster than <=?
Is if (a < 901) faster than if (a <= 900)? Not exactly as in this simple example, but there are slight p
58
votes
7
answers
1.9K
views
Fastest way to determine if an integer is between two integers (inclusive) with known sets of values
Is there a faster way than x >= start && x <= end in C or C++ to test if an integer is between t
50
votes
3
answers
389
views
What is the runtime performance cost of a Docker container?
I'd like to comprehensively understand the run-time performance cost of a Docker container. I've fou
63
votes
2
answers
2K
views
arrayfun can be significantly slower than an explicit loop in matlab. Why?
Consider the following simple speed test for arrayfun: T = 4000; N = 500; x = randn(T, N); Func1 = @(a) (3*a^
51
votes
12
answers
1.9K
views
Why is MATLAB so fast in matrix multiplication?
I am making some benchmarks with CUDA, C++, C#, Java, and using MATLAB for verification and matrix generation.
60
votes
8
answers
658
views
LINQ: Not Any vs All Don't
Often I want to check if a provided value matches one in a list (e.g. when validating): if (!acceptedValues.A
55
votes
16
answers
1.4K
views
Is it better to call ToList() or ToArray() in LINQ queries?
I often run into the case where I want to eval a query right where I declare it. This is usually because I nee
49
votes
10
answers
1.2K
views
Which method performs better: .Any() vs .Count() > 0?
in the System.Linq namespace, we can now extend our IEnumerable's to have the Any() and Count() extension
51
votes
2
answers
1.1K
views
Unexpected outcome of node.js vs ASP.NET Core performance test
I am doing a quick stress test on two (kinda) hello world projects written in node.js and asp.net-core. Both o
55
votes
16
answers
1.5K
views
numpy: most efficient frequency counts for unique values in an array
In numpy / scipy, is there an efficient way to get frequency counts for unique values in an array? Something
60
votes
11
answers
1.4K
views
Most efficient way to map function over numpy array
What is the most efficient way to map a function over a numpy array? The way I've been doing it in my cur
53
votes
7
answers
758
views
Why use AJAX when WebSockets is available?
I've been using WebSockets for a while now, I have chosen to create an Agile project management tool for
54
votes
12
answers
1.4K
views
Is String.Format as efficient as StringBuilder
Suppose I have a stringbuilder in C# that does this: StringBuilder sb = new StringBuilder(); string cat = "ca
