During some lock debugging on a dual-core Linux system I noticed that threads are blocked acquiring `cs_vNodes` and `cs_main` for long periods when the system is under moderate load from unrelated processes -- the unlucky lock acquirer is waiting for single-digit seconds once every 10 minutes or so (not coinciding with new blocks) up to around a 30 second wait every few hours. It looks like `ThreadMessageHandler` is taking locks and then due to being set to `THREAD_PRIORITY_BELOW_NORMAL`, it's being descheduled (even in trivial lock-holding regions like `GetHeight`) and holding up for arbitrarily long periods other threads that use these core locks.

So I'm wondering, what are the benefits of running the message handler at low priority?

setCategories.count(string(category)) == 0)
            return false;
    }
    return true;
}
/**
 * fStartedNewLine is a state variable held by the calling context that will
 * suppress printing of the timestamp when multiple calls are made that don't
 * end in a newline. Initialize it to true, and hold it, in the calling context.
 */
static std::string LogTimestampStr(const std::string &str, bool *fStartedNewLine)
{
    string strStamped;
    if (!fLogTimestamps)
        return str;
    if (*fStartedNewLine) {
        int64_t nTimeMicros = GetLogTimeMicros();
        strStamped = DateTimeStrFormat("%Y-%m-%d %H:%M:%S", nTimeMicros/1000000);
        if (fLogTimeMicros)
            strStamped += strprintf(".%06d", nTimeMicros%1000000);
        strStamped += ' ' + str;
    } else
        strStamped = str;
    if (!str.empty() && str[str.size()-1] == '\n')
        *fStartedNewLine = true;
    else
        *fStartedNewLine = false;
    return strStamped;
}
int LogPrintStr(const std::string &str)