I have to disagree with your proposed heap settings.  You have set the young 
generation to use most of the heap, and have allowed for only a very small  
tenured generation.  Using your settings, every collection will be a major 
collection -- the Sun JVM performs a major collection if there is not enough 
space to hold all of the objects in the young generation during a collection 
(this is one of the things that we tweaked in our JVM, which is based on Sun's 
source -- we calculate how many objects will be tenured first before 
determining if we need a major collection).  Major collections tend to be 
fairly expensive, thought that is somewhat reduced based on the size of your 
tenured generation.

Recommeded heap ratios are for the tenured generation to be approximately two 
times the size of the young generation.  Our recommended sizes are 1200MB for 
the heap and 400MB for the young generation.  Of course, we also recommend that 
you have 2GB of RAM to do this.  And by the way, this recommendation is only a 
starting point, you have to tune from there and to do that you have to gather 
and analyze the garbage collection statistics.  I have written several white 
papers on this topic, they are available at www.cmg.org, but you have to be a 
CMG member to see them.  If there is interest, I will see about posting them 
somewhere more accessible.

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