We've certainly seen that F5 load balancers cause problems
just like your
seeing when used with LDAP. They just slow things down way
too much to be worthwhile.
Do you have any facts/numbers to back this up? I've never seen F5's
slow things down noticably. The most common problem load balancers
introduce are idle timeout mismatches (where the LB times out and drops
an idle connection from it's table that the client and server don't know
was dropped, so leave lots of orphaned connections hanging open on both
sides, which in turn does cause problems - one of which could be
performance). Trivial to fix with proper idle timeout
configuration/coordination on the backend server and LB.