Have you know that & operator, which is slow now has a alternative (StringBuilder)
The System.Text.StringBuilder class finally gives Visual Basic developers the tools they need to do efficient string manipulation operations. StringBuilder provides a buffer-oriented mechanism to manipulate string information. String concatenation is not its only use, but that's the most common one.
Otherwise, you might not know it, but Visual Basic cannot combine two strings. What it does is create a new string object that contains the combined source strings' values. Using the & results in a new string being created each time you use it (unless it is used in a Const statement, in which case it is evaluated at compile time). For instance,
myString = "text" & "text" & "text" causes the creation of three strings just to assign one to the variables. This leads to unnecessary—or at least unwanted—memory allocation to build just one string. And it gets much worse as you add more to the string.
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