Questions related to improving application performance, this can be range from selection software architecture to selection of algorithms.

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-2
votes
1answer
64 views

Duplicate code to avoid performance decrease due to function calls? [on hold]

I have a simple list in Java that I need to search using one of two methods. The first method simply returns the position in the list of the first matching element. The second filters out any elements ...
0
votes
1answer
125 views

Why do successive iOS versions take longer to run the same task on the same hardware?

Updating the iOS version on an old iPhone tends to make basic operations like startup, placing calls, and checking settings take longer. The change from eg iOS 7 to 8 on an iPhone 4S has a very ...
4
votes
2answers
76 views

How to facilitate thread-safe access to large set of shared variables?

I have 2 sets--inputs and outputs--of 70 32-bit integer variables and 70 bools (140 vars altogether). These need to be accessed and modified from 3 threads. What is an appropriate design pattern to ...
3
votes
6answers
260 views

How efficient is malloc and how do implementations differ?

If I use malloc, does malloc always use the same algorithm regardless of what it is allocating or does it look at the data and select an appriopriate algorithm? Can we make malloc faster or smarter ...
2
votes
1answer
81 views

Optimizing the exponential smoothing of a big array

I have a large set of values (let's say 1M entries) where I need to apply an exponential smoothing algorithm, but only incrementing one value at a time (all others decay to zero). The trivial ...
3
votes
5answers
105 views

Use Exceptions for control flow in order to increase performance?

I add a lot of elements to a list of lists. If the list of lists my element should be saved to, does not exist yet, I handle this by catching an exception and adding a new list to my list of lists. ...
5
votes
6answers
569 views

How much do function calls impact performance?

Extracting functionality into methods or functions is a must for code modularity, readability and interoperability, especially in OOP. But this means more functions calls will be made. How does ...
0
votes
2answers
83 views

JSON or XML or other - most time efficient for largely “read” of structured data

Considering that using a relational DB or other hierarchical or such databases is not an option, looking for the alternative approach using a simple (but very fast, efficient, distributed KV-store). ...
1
vote
4answers
112 views

is stored procedure having multiple UNION efficient than running all SQL's in parallel?

I have below in my stored proc if then SELECT TABLE1.COLUMN1,TABLE1.COLUMN2,TABLE1.COLUMN3,TABLE1.COLUMN4 FROM TABLE1,TABLE2 where criteria1 (covers functionality 1) UNION SELECT ...
-1
votes
2answers
90 views

Does sql use hastables for indexes? [closed]

Are there other ways of indexing?, Which are the more used? Does sql have an standard for indexes, it uses hash tables?
4
votes
0answers
55 views

Estimate if benchmark sampling difference is significative

In order to estimate the fastest function in various cases in a non fully deterministic context, I'm running an experiment calling one or the other at random and recording the duration of the ...
0
votes
0answers
19 views

Finding performance (network perspective) differences between mobile websites and their corresponding applications?

I'm researching performance differences when using an application, compared to its mobile website counterpart. To my help I looked into what other people define as performance(since it's a broad term) ...
2
votes
0answers
69 views

Maximising data processing speed: in-memory or write to db first?

Currently working on a system which allows users to upload data files, which we then "clean" (i.e. process in various ways). Speed of processing and return to the user is an important consideration, ...
1
vote
1answer
78 views

Clairvoyance in caching - optimal strategies?

This question relates to the question here, but I'll generalise it so that you can answer effectively without reading all of that. Context: Imagine you had a large set of data greater than your ...
2
votes
1answer
67 views

Caching in '3D' - data-structures and octree recursion - hrrm!

The Situation: I have 68GB of data that is conceptually realized as a 3D matrix of 8-bit values with dimension 4096*4096*4096. I need to access multiple sections of this data for processing in a ...
25
votes
11answers
2k views

How to deal with misconceptions about “premature optimization is the root of all evil”?

I've encountered many people who are dogmatically against anything which can be considered "optimization" in the general English-language sense of the word, and they very often quote verbatim the ...
1
vote
1answer
60 views

«Heavy» object initialization: within each thread or outside and then pass it to the threads as parameter?

Let say there is an array of strings, I have to process. I'm using a «heavy» third-part object which gets the string and performs its analysis. In order to optimize a performance, I create a number of ...
-7
votes
1answer
177 views

Java: Why's this For-Loop thousands of times slower?

So I have a simple method I'm calling millions of times a second, and I noticed that it was taking 16% of all processing time!! The offensive routine is as follows: public void placeHolder(){ ...
4
votes
1answer
76 views

How do you handle Performance tasks in Agile?

How is the Agile process affected if a stakeholder requests that a specific operation in the software need to perform better? This could mean that it runs very slow for a customer's needs (even with ...
-1
votes
4answers
179 views

Nested For Loops JavaScript

I have an app which gets data from the database (MongoDB) in JSON format. The returned data contains nested arrays and I want to access the values in the nested arrays. The returned JSON format looks ...
1
vote
0answers
68 views

Guaranteed message sending for messages of different priority for different modules

We have created a message que system using priority messages. The idea behind this is as follows: We have a list of clients. All clients know if (and what kind of priority) messages they have ...
8
votes
2answers
169 views

Why does expressing calculations as matrix multiplications make them faster?

In Google's MNist tutorial using TensorFlow, a calculation is exhibited in which one step is equivalent to multiplying a matrix by a vector. Google first shows a picture in which each numeric ...
0
votes
1answer
264 views

How could this be considered performant code?

I came across this (Java) code yesterday and can't figure out why someone would have done this in any language. In what scenario, language, paranoid delusion would "removing" values from an ...
3
votes
1answer
319 views

Bad c++ code design? [closed]

This is bothering me a long time. I feel like I am doing mistakes on the code design relative to the performance. I never had any teacher to indicate my mistakes so its hard to me to make it right in ...
1
vote
0answers
24 views

Distributed Design to Speed Up Video Processing

Currently I have one web server running Django, which takes a series of images from a user, uploads them to an Amazon S3 bucket, and finally calls an Amazon Lambda instance, which runs a python script ...
1
vote
0answers
41 views

Best way to handle multiple proxies and HTTP requests

I need to develop a solution for a problem that requires multiple HTTP/ Socks proxies for different HTTP requests. The solution needs to be cross platform. Here is my idea how it needs to work: ...
1
vote
4answers
322 views

What is the ninja performance gap, why is it so large, and how can we overcome it?

According to this abstract: The "Ninja gap" [...] is the performance gap between naively written C/C++ code that is parallelism unaware (often serial) and best-optimized code on modern ...
1
vote
2answers
96 views

Load to list in one loop and then process list in another or do it all at once

I have a dataset full of rows that I must initialize into myclass and then process. I am currently looping through each row in the dataset, initializing a new instance of myclass, then adding that ...
2
votes
3answers
135 views

Is denormalising a data structure essentially a code optimisation, to which the normal rules apply?

One of Bloch's Effective Java items 55: Optimize judiciously extends Jackson's rules on optimization: Rule no. 1: Don't optimise! Rule no. 2 (for experts): Don't optimise yet! Extra ...
0
votes
1answer
60 views

Does variable type specification lead to any performance difference?

Let's say I have a very long method which basically creates a responsive and resizable layout for a user interface by using a few fixed values and a few variable ones taken from an element's ...
0
votes
0answers
84 views

Options for implementing database and programming logic for statistics application?

I am implementing a statistics driven web application. The statistics relate to sporting events. Right now I have a postgresql database with a table that holds a row for each match. This is a ...
4
votes
0answers
89 views

Using mysql 5.7 Json Columns for EAV

I am developing an e-commerce product and I have been able to implement all functionality and am left with allowing users to create additional attributes for a product. Right Now I have two options. ...
0
votes
0answers
104 views

Advice on program performance after changes

So, the situation is like this: For the past two years, I have implemented a class in c# which is used to filter different fields from different tables in database (SQL), for reporting purposes. Now ...
6
votes
1answer
359 views

Does unused code affects the assembly after startup (Memory for example)?

Disclaimer: I come from a PHP background. In PHP, I could have thousands files, which are never loaded, if not needed, due to the autoloader feature (If some code is needed, it would be loaded) How ...
6
votes
5answers
554 views

How to design a complex REST API considering DB performance?

I've been following some tutorials on how to design REST APIs, but I still have some big questions marks. All these tutorials show resources with relatively simple hierarchies, and I would like to ...
2
votes
1answer
111 views

Improving sampling algorithm

I am having a bit of trouble designing a new feature at the moment. It is part of a resource management system. I was wondering if anyone has experience doing anything similar. I'll try to explain: ...
1
vote
0answers
32 views

How can I test for performance issues in a specific piece of code? [duplicate]

I've inherited a problem from a programmer that isn't with our group anymore - a piece of our application suffers from performance issues under a particular set of circumstances. I can replicate ...
6
votes
6answers
271 views

Should I always store parsed data in database before manipulating?

I am about to start a new project which involves taking an excel file, parsing the data (php-excel-reader) and then using the parsed values in a HTML email. My question is pretty simple. Is it better ...
3
votes
1answer
123 views

How are objects treated in an anonymous inner class?

Lets take this for example... entryText.addTextChangedListener(new TextWatcher() { TextView wordCount = (TextView) findViewById(R.id.wordCount); TextView charCount = (TextView) ...
-1
votes
1answer
98 views

Speeding up appending text in C# [duplicate]

I'm trying to append text to a large amount of strings (in the thousands), and also do some other string manipulations. However, I have about 60 lines of if/else and string appending and it takes ...
5
votes
1answer
185 views

What is the most efficient way to implement a RESTful client app?

I am working on a web application for ranking some products based on some factors. The user send a search query to 5 restful webservices which by their turn send a response in a JSON format and ...
44
votes
6answers
4k views

Does immutability hurt performance in JavaScript?

There seems to be a recent trend in JavaScript towards treating data structures as immutable. For example, if you need to change a single property of an object, better to just create a whole new ...
3
votes
0answers
97 views

Tips for optimizing javascript code. a year's worth of Dates

I am playing around with the date object, i made a function that generates a bunch of dates, and applies some function on each date. For a month's worth, it is fine about 2.5ms on my pc, ff and ...
0
votes
1answer
51 views

When > apply a performance and memory profiler? [closed]

Based on your experience, when do you need to perform a performance and memory profiler for a web development project in C#? Today, Im newbie in performance and memory profiling.
3
votes
1answer
254 views

Best practice for Restful API that perform heavy calculations (Image Processing)

We are currently developing an image processing restful api. Server performs some CPU-heavy computations image processing upon request and return the image to the client. We want to make this a ...
2
votes
0answers
70 views

Dealing with big data [closed]

I am on a project dealing with a lot of data in the form of images and videos (Data related to wind engineering). My requirement is to build a predictive algorithm based on the data I have. I have ...
0
votes
1answer
153 views

Low cost exceptions implementation using metaprogramming [closed]

(preface - boring stuff, feel free to skip down to the implementation details) I need to provide exception handling to a language I am working on. It "compiles" to a subset of C, and since I don't ...
0
votes
0answers
90 views

Best datastructure to use

I am using Amazon's dynamodb nosql database and as a result I need to think of some ways to do certain operations to fit into their limits (e.g 4k item limit, can't combine small items into the same ...
1
vote
1answer
152 views

How to improve performance for serializing and deserializing a large object graph?

I have a large object graph in .NET (F# as it happens) that I need to persist to disk and then will load again periodically for use in a calculation. The performance of deserializing is more ...
12
votes
6answers
1k views

In general, is it worth using virtual functions to avoid branching?

There seems to be rough equivalents of instructions to equate to the cost of a branch miss virtual functions have a similar tradeoff: instruction vs. data cache miss optimization barrier If ...