I played briefly with the Zend Optimizer, which promises to speed up PHP scripts (such as those that create this journal) by 40%-100%. In practice I found that when the Optimizer was enabled, single-script execution speed actually slowed by a few thousands of a second.
The statistics are not significant, but I sure didn’t see any improvement in performance.
I tested various levels of optimization with similar results. I wonder if the Alternative PHP Cache would yield better results? (But I don’t wonder about it enough to warrant actually testing it… this site is, regrettably, a long way from “heavily loaded.”)