The answer: it's summer.
The publishing industry doesn't exactly go into hibernation during the summer months, but it's fair to say that business slows down substantially between Memorial Day and Labor Day. Aside from physical production, everything winds down a bit: offers from agents, acquisitions from editors, &c, &c. It's sort of the calm before the storm of the holiday season (October through December).
If you're currently submitting a manuscript, don't be surprised if it takes longer than usual to hear back. Not only is there an industry-wide downtrend in acquiring new work, but the majority of publishing professionals take vacation during the summer months, meaning that at any given time a large percentage of available staff are out of the office. Even if your agent is around, if (s)he depends on his/her assistant to filter submissions and that assistant is in Cancún for the week, you probably won't be hearing back about your novel for at least that long.
My advice? Spend the summer writing. As I've mentioned before, I
What about you, mes auteurs? Are you submitting now? If not, how are you spending your writing-related time?