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?

#ifndef BITCOIN_COMPAT_H
#define BITCOIN_COMPAT_H
#if defined(HAVE_CONFIG_H)
#include "config/bitcoin-config.h"
#endif
#ifdef WIN32
#ifdef _WIN32_WINNT
#undef _WIN32_WINNT
#endif
#define _WIN32_WINNT 0x0501
#ifndef WIN32_LEAN_AND_MEAN
#define WIN32_LEAN_AND_MEAN 1
#endif
#ifndef NOMINMAX
#define NOMINMAX
#endif
#ifdef FD_SETSIZE
#undef FD_SETSIZE // prevent redefinition compiler warning
#endif
#define FD_SETSIZE 1024 // max number of fds in fd_set
#include <winsock2.h>     
#include <mswsock.h>
#include <windows.h>
#include <ws2tcpip.h>
#else
#include <sys/fcntl.h>
#include <sys/mman.h>