performance

Symmetric Encryption: Performance Questions

Does the performance of a symmetric encryption algorithm depend on the amount of data being encrypted? Suppose I have about 1000 bytes I need to send over the network rapidly, is it better to encrypt 50 bytes of data 20 times, or 1000 bytes at once? Which will be faster? Does it depend on the algorithm used? If so, what's the highest pe...

SQL Server Index cost

I have read that one of the tradeoffs for adding table indexes in SQL Server is the increased cost of insert/update/delete queries to benefit the performance of select queries. I can conceptually understand what happens in the case of an insert because SQL Server has to write entries into each index matching the new rows, but update and...

Looking for a fast hash-function.

Hello, I'm looking for a special hash-function. Let's say I have a large list of strings, if I order them by their hash-values they should be ordered quasi randomly. The most important point is: it must be super fast. I've tried md5 and sha1 and they're using to much cpu power. Clashes are not a problem. I'm using javascript, so it ...

Calling sp and Performance strategy.

Hi I find my self in a situation where I have to choose between either creating a new sp in database and create the middle layer code. so loose some precious development time. also the procedure is likely to contain some joins. Or use two already existing sp(s), the problem of this approach is that I am doing two round trips to databas...

ASP.NET Caching : Good As Well As Bad ! Page shows old content!

I have an ASP.NET website where i have implemented page level caching using the OutPutCache directive.This boosted the page performance.My pages has few parts(Some buttons,links and labels) which are specific to the logged in user.If user is not logged in,they will see different links.Now Since i implemented the page level caching,Even a...

Will more CPUs/cores help with VS.NET build times?

I was wondering if anyone knew whether Visual Studio .NET had a parallel build process or not? I have a solution with lots of projects, every project has lots of markup/code, lots of types, etc. Just sitting there with intellisense on runs it up to about 700MB. But the build times are really slow and only seem to max out one of my two cp...

Question about Cost in Oracle Explain Plan

When Oracle is estimating the 'Cost' for certain queries, does it actually look at the amount of data (rows) in a table? For example: If I'm doing a full table scan of employees for name='Bob', does it estimate the cost by counting the amount of existing rows, or is it always a set cost? ...

Regex vs. Manual comparison. Which is faster?

Hello, in writing a scripting engine, I have functions like (psuedo-code) function is_whitespace?(char c){ return c==' ' || c=='\t' || c=='\r' || c=='\n'; } Well, my question is which is faster in most langugaes? That or using regex like function is_whitespace?(char c){ return regex_match('\s',c); } The chief languages I'm conc...

Why is drawing to OnPaint graphics faster than image graphics?

I'm looking for a way to speed up the drawing of my game engine, which is currently the significant bottleneck, and is causing slowdowns. I'm on the verge of converting it over to XNA, but I just noticed something. Say I have a small image that I've loaded. Image img = Image.FromFile("mypict.png"); We have a picturebox on the scr...

Testing perceived performance

I recently got a shiny new development workstation. The only disadvantage of this is that the desktop apps I'm developing now run very, very fast, and so I fear that parts of the code that would be annoyingly slow on end users' machines will go unnoticed during my testing. Is there a good way to slow down an application for testing? I...

Precision of cos(atan2(y,x)) versus using complex <double>, C++

Hi all, I'm writing some coordinate transformations (more specifically the Joukoswky Transform, Wikipedia Joukowsky Transform), and I'm interested in performance, but of course precision. I'm trying to do the coordinate transformations in two ways: 1) Calculating the real and complex parts in separate, using double precision, as below:...

C# performance methods of receiving data from a socket?

Lets assume we have a simple internet socket, and its going to send 10 megabytes (because i want to ignore memory issues) of random data through. Is there any performance difference or a best practice method that one should use for receiving data? The final output data should be represented by a byte[]. Yes i know writing an arbitrary a...

How to find which method makes my iPhone app slow ?

Currently I am working on a production app. One function acts like the settings.app on iPhone. When the user click a cell of a tableView, as shown below http://www.penguintech.net/images/stackoverflow/1.png It will push another view, which includes a textfield to let user input something. However, on both simulator and device, after t...

Why AQTime slows execution even when profiling is not on, and can anything be done for it?

Hi! In AQTime for Delphi, it boasts to be very fast to get to the trouble spots by using areas and triggers etc. But it seems to me, that especially if you have very much code in the areas to profile, then the execution slows down dramatically even when the profiling is NOT on. For example, if I want to profile a specific routine late ...

How to increase performance over GDI's DrawImage(Unscaled)?

In my user control's paint handler I iterate over a collection of predefined Bitmap objects and draw them to the client area thusly: C# version: private void Control_Paint(object sender, PaintEventArgs e) { Graphics g = e.Graphics; foreach (BitmapObj bmpObj in _bitmapObjCollection) { g.DrawImageUnscaled(bmpObj.Bitmap, b...

CouchDB query performance

If the number of documents is more will the querying of data gets slower in CouchDB? Example Scenario: I have a combobox in a form for customer name. When the user types the customer name, I have to do autofilling. There will be around 10k customer documents in the CouchDB. I understand that i have to create a view to do the same. C...

WPF Binding Failure performance hit vs Exception

when we bind to heterogeneous collection of objects, not all objects have the same set of properties. in the output window we get a message like: System.Windows.Data Error: 39 : BindingExpression path error: 'RoundingFactor' property not found on 'object' ''MultiLineTextMarkingScheme' (HashCode=7262386)'. BindingExpression:...

Speed Difference between native OLE DB and ADO.NET

I'm looking for suggestions as well as any benchmarks or observations people have. We are looking to rewrite our data access layer and are trying to decide between native C++ OLEDB or ADO.NET for connecting with databases. Currently we are specifically targeting Oracle which would mean we would use the Oracle OLE DB provider and the OD...

Is there a way to reuse an XmlReader?

I have a process that uses an XmlReader. I have already done a lot to squeeze maximum performance out of it. So far we have had huge gains from using the Reader as opposed to XmlDoc or DataSet.GetXml(). We expect to get XML many times a second and I would like to avoid the overhead of recreating the reader every time. I have already cach...

Response Time is different for mulitiple execution of the application with the same request Performance problem

My java application functionality is to provide reference data (basically loads lots of data from xml files into hashmap) and hence we request for one such data from the hashmap based on a id and we have such multiple has map for different set of business data. The problem is that when i tried executing the java application for the same ...