I was supprised with the last results from the XmlWriters and compression stream performance post and figured I did something wrong. So today I re-ran my test and got the results I expected after some data manipulation. The results aren't shocking; writing to a memory stream is about 8% faster when you increase the intialcapacity from 256 bytes to 131072 bytes, further increasing doesn't improve the performance further. Naturally this depends on the data, only 6 xmldocuments I used in this test were greater than 131072 bytes.

Methodology:

I saved each xml document to the memorystream 100 times for each initial capacity and removed the 10 best and 10 worst results. The results are relative to the performance of the stream with an initial capacity of 256 bytes.

Notes:

My data is not your data; always do your own testing to determine the 'best' initial capacity for your situation.