That's a good optimisation.  I'll add that next time I update SVN.

More generally, we could also consider this:

        dbenv.set_lk_max_objects(10000);
        dbenv.set_errfile(fopen(strErrorFile.c_str(), "a")); /// debug
        dbenv.set_flags(DB_AUTO_COMMIT, 1);
+       dbenv.set_flags(DB_TXN_NOSYNC, 1);
        ret = dbenv.open(strDataDir.c_str(),
                         DB_CREATE     |
                         DB_INIT_LOCK  |
                         DB_INIT_LOG   |

We would then rely on dbenv.txn_checkpoint(0, 0, 0) in CDB::Close() to flush after wallet writes.