performance of moved portal areas really poor - CachedNavDirty?

Hi,

we have a busy Sharepoint 2003 portal that has been growing and
growing. however its architecture has plenty of capacity in its
design.

in recent weeks we have seen the database CPU max out, causing
outtage. the situation is only rectified over night

we are scatching our heads to what sharepoint is doing, we see that
the site database WEBS table contains a field called CachedNavDirty.
in nearly all our database CPU maxouts, this has been a non-zero
value.

can anyone shed any light on:
* this field; CachedNavDirty
* whether moving a site in site settings kicks off any performance
intensive processes
* has anyone written anything to clear cachednavdirty directly?

many thanks
tristian o'brien
portal solution architect
CENTRICA PLC

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