poor performance with ext3

hi all,
I am quite forced to use ext3 since I'm using a remotely hosted linux 
box with RH ES 2.1.
I am using Zope 2.7.2 and the DirectorySotrage 1.9.
I switched to DirectoryStorage since I had memory eating problems (I 
host like 30 zope sites in 3 instances). Now the memory usage is a lot 
stabler, but I'm running in performance issues, since a site can take up 
to 30 seconds to load.
CPU usage seems to be much higher than before, but I think the major 
problem is disk I/O.
Is there a way to optimize some values for the ext3 filesystem? Of 
course I used the bushy type. Maybe some /proc tweaking?
I also disables md5 checking in the settings file (is a reboot 
sufficient to apply this changes? since I always get high cpu).

Please please help.
Thanks in advance.
Lorenzo


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