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?

/**
 * Server/client environment: argument handling, config file parsing,
 * logging, thread wrappers
 */
#ifndef BITCOIN_UTIL_H
#define BITCOIN_UTIL_H
#if defined(HAVE_CONFIG_H)
#include "config/bitcoin-config.h"
#endif
#include "compat.h"
#include "tinyformat.h"
#include "utiltime.h"
#include <exception>
#include <map>
#include <stdint.h>
#include <string>
#include <vector>
#include <boost/filesystem/path.hpp>
#include <boost/signals2/signal.hpp>
#include <boost/thread/exceptions.hpp>
static const bool DEFAULT_LOGTIMEMICROS = false;
static const bool DEFAULT_LOGIPS        = false;
static const bool DEFAULT_LOGTIMESTAMPS = true;
class CTranslationInterface