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Why is lock(this) {…} bad?
...t deciding what to lock. Be aware that taking a lock involves cache-flush CPU operations and is somewhat expensive. In other words: do not lock and update each individual integer. :)
– Zan Lynx
Oct 31 '08 at 0:12
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Java HashMap performance optimization / alternative
...hat does this accomplish? Adding a constant to every hash value just burns cpu cycles without accomplishing anything useful. Lesson here: Adding complexity to a hash function is not the goal. The goal is to get a broad range of different values, not just to add complexity for the sake of complexity....
How to decide when to use Node.js?
... have a lot of concurrent connections and each request only needs very few CPU cycles, because the event loop (with all the other clients) is blocked during execution of a function.
A good article about the event loop in Node.js is Mixu's tech blog: Understanding the node.js event loop.
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How to append rows to an R data frame
...t(r)
For 1E5 rows (measurements done on Intel(R) Core(TM) i7-4710HQ CPU @ 2.50GHz):
nr function time
4 data.frame 228.251
3 sqlite 133.716
2 data.table 3.059
1 rbindlist 169.998
0 placebo 0.202
It looks like the SQLite-based sulution, although r...
Undefined, unspecified and implementation-defined behavior
...bar), where bar is an int and boz() is a function returning int. Assume a CPU where parameters are expected to be passed in registers R0-R1. Function results are returned in R0; functions may trash R1. Evaluating "bar" before "boz()" would require saving a copy of bar somewhere else before callin...
What are the main performance differences between varchar and nvarchar SQL Server data types?
... highlighting how bad nvarchar performance can be...
SQL Server uses high CPU when searching inside nvarchar strings
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Why does changing 0.1f to 0 slow down performance by 10x?
... sets FTZ (flush to zero) and DAZ (denormal are zero) in the MXCSR, so the CPU never has to take a slow microcode assist for denormals.
– Peter Cordes
Jan 16 '19 at 10:23
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What is the performance cost of having a virtual method in a C++ class?
...cache misses on execution (deliberately, since I was trying to examine the CPU pipeline in isolation), so they discount that cost.
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How much is the overhead of smart pointers compared to normal pointers in C++?
...tps://vimeo.com/131189627
It goes deep into the implementation details and CPU architecture for write barriers, atomic locks etc. once listening you will never talk about this feature being cheap. If you just want a proof of the magnitude slower, skip the first 48 minutes and watch him running examp...
What are the differences between a multidimensional array and an array of arrays in C#?
...nal but my guess is that it has to do with some optimalization made on the CPU
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