While the thread pool event queue size per tag is of note, the one that makes me consider value change events a last option is this one:
So, not only is there a thread pool event que per tag, but all tag event executions are also in a limited thread pool. This means that only 3 threads can be executing at one time. If you litter your tags with value change scripts it isn't hard at all to hit this limit, and then the chance that you run into the pool queue size per tag only increases.