Zabbix proxy doesn't handle large backload gracefully

If the proxy loses connectivity with the server for an extended period of time and accumulates a large amount of history, when connectivity is reestablished, it takes a very large amount of time for the proxy to send the backlogged history data.

This seems to be caused by at least 2 things:

• The proxy has a hard-coded limit of only sending 1000 entries at once (ZBX_MAX_HRECORDS).
• The trapper process has a limit of only processing 512k of JSON data (which I'm guessing is the reason for the above 1000 entry limit).