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?

{
    if (mapArgs.count(strArg))
        return atoi64(mapArgs[strArg]);
    return nDefault;
}
bool GetBoolArg(const std::string& strArg, bool fDefault)
{
    if (mapArgs.count(strArg))
        return InterpretBool(mapArgs[strArg]);
    return fDefault;
}
bool SoftSetArg(const std::string& strArg, const std::string& strValue)
{
    if (mapArgs.count(strArg))
        return false;
    mapArgs[strArg] = strValue;
    return true;
}
bool SoftSetBoolArg(const std::string& strArg, bool fValue)
{
    if (fValue)
        return SoftSetArg(strArg, std::string("1"));
    else
        return SoftSetArg(strArg, std::string("0"));
}
static const int screenWidth = 79;
static const int optIndent = 2;
static const int msgIndent = 7;
std::string HelpMessageGroup(const std::string &message) {