Which version of glassfish are you using ?.
Just a guess, but you may want to experiment with the pool properties :
com.sun.jndi.ldap.connect.pool : the default value for this is "true" in LDAPRealm, which means pooling is enabled by default.
com.sun.jndi.ldap.connect.pool.protocol : the default value for this is "plain ssl"
com.sun.jndi.ldap.connect.pool.maxsize : the default value for this is "5"
So you may want to see if setting the following property under your ldap realm will help
<property name="pool-size" value="20"/>
Also can you try GlassFish from the following link and tell us if there is any improvement.
Because there was a custom socket factory added for ldaps connections.
https://sailfin.dev.java.net/downloads/v1-b60b.html
[Message sent by forum member 'kumarjayanti' (kumarjayanti)]
http://forums.java.net/jive/thread.jspa?messageID=320784