Updated: 11/29/2006

You can get better performance from your Visual Basic programs by choosing the right operators.

This article is intended to help developers improve the run-time performance of their Visual Basic applications running in .Net by explaining how to choose the correct operators for certain common operations.

One of the primary goals of each new version of Visual Basic is to perform faster than previous versions. But performance still depends on how you design your program. This article describes some important considerations that can help you optimize your application's performance.

Some of the recommendations in this article might represent a negligible difference within one statement, but the performance gain can be greatly amplified inside a loop or a frequently called procedure. Code blocks that are executed many times are good candidates for optimization.

Division:  \  vs.  /

Divide integral values with the \  (back slash) operator when you do not need decimal points or fractional values.  The \ operator is the integral division operator and it is up to 10 times faster than the / (forward slash) operator.

Compound Assignment Operators:  a += b   vs.  a = a + b

Compound assignment statements first perform an operation on an argument before assigning it to another argument.  Example:

a += b  

In the example above, b is added to the value of a, and that new value is then assigned to a. Compound assignment operators are more concise than their constituent operators (separate + and =). Compare the statement above to the one below.  The statement above is a shorthand equivalent of the statement below.

a = a + b

Compound assignment operators are faster.  If you are operating on an expression instead of a single variable, for example an array element, you can achieve a significant improvement with compound assignment operators.

Compound assignment operators for numbers:

Compound operator for strings:    &=      Example:

Dim a As String = "First "

a &= "Name"  

Result:  First Name

Concatenation:  &  vs. +

Use the & concatenation operator instead of the + operator to increase the speed of concatenations. Performance of the & and + operators are only equivalent if both operands are type String.  If not, the + operator is late bound and must perform type checking and conversions.