Collect consecutive pstack and prstat output of the Directory Server during the period when the performance drops as described in Analyzing Data About a Unresponsive Process: an Example. For example, you could use the following script on Solaris to gather pstack and prstat information:
#!/bin/sh i=0 while [ "$i" -lt "10" ] do echo "$i/n" date= `date"+%y%m%d:%H%M%S" prstate -L -p $1 0 1 > /tmp/prstate.$date pstack $1 > /tmp/pstack.$date i=`expr $i + 1` sleep 1 done |