Your first version, which puts everything into a StringBuilder
and then writes it, will consume the most memory. If the text is very large, you have the potential of running out of memory. It has the potential to be faster, but it could also be slower.
The second option will use much less memory (basically, just the StreamWriter
buffer), and will perform very well. I would recommend this option. It performs well--possibly better than the first method--and doesn't have the same potential for running out of memory.
You can speed it quite a lot by increasing the size of the output buffer. Rather than
File.AppendText("filename")
Create the stream with:
const int BufferSize = 65536; // 64 Kilobytes
StreamWriter sw = new StreamWriter("filename", true, Encoding.UTF8, BufferSize);
A buffer size of 64K gives much better performance than the default 4K buffer size. You can go larger, but I've found that larger than 64K gives minimal performance gains, and on some systems can actually decrease performance.
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