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?

{
    int nBestHeight = g_signals.GetHeight().get_value_or(0);
    int64_t nTime = (fInbound ? GetAdjustedTime() : GetTime());
    CAddress addrYou = (addr.IsRoutable() && !IsProxy(addr) ? addr : CAddress(CService("0.0.0.0",0)));
    CAddress addrMe = GetLocalAddress(&addr);
    GetRandBytes((unsigned char*)&nLocalHostNonce, sizeof(nLocalHostNonce));
    if (fLogIPs)
        LogPrint("net", "send version message: version %d, blocks=%d, us=%s, them=%s, peer=%d\n", PROTOCOL_VERSION, nBestHeight, addrMe.ToString(), addrYou.ToString(), id);
    else
        LogPrint("net", "send version message: version %d, blocks=%d, us=%s, peer=%d\n", PROTOCOL_VERSION, nBestHeight, addrMe.ToString(), id);
    PushMessage(NetMsgType::VERSION, PROTOCOL_VERSION, nLocalServices, nTime, addrYou, addrMe,
                nLocalHostNonce, strSubVersion, nBestHeight, !GetBoolArg("-blocksonly", DEFAULT_BLOCKSONLY));
}
banmap_t CNode::setBanned;
CCriticalSection CNode::cs_setBanned;
bool CNode::setBannedIsDirty;
void CNode::ClearBanned()
{
    LOCK(cs_setBanned);
    setBanned.clear();
    setBannedIsDirty = true;
}
bool CNode::IsBanned(CNetAddr ip)