Major performance issues with bytea performance

[regevbr]

Hi,

I encountered the exact same issue as #1286 wheres a simple query to retrieve a 100mb bytea column from a one table, one row DB takes forever and causes the cpu to spike at 100%, rendering my node instance unresponsive.

After investigating, I think I found the cause in the pg-protocol package

node-postgres/packages/pg-protocol/src/parser.ts

Lines 91 to 93 in ea6ac2a

	combinedBuffer = Buffer.allocUnsafe(this.remainingBuffer.byteLength + buffer.byteLength)
	this.remainingBuffer.copy(combinedBuffer)
	buffer.copy(combinedBuffer, this.remainingBuffer.byteLength)

Which suffers from the same thing as the original issue - too many allocations and buffer copies going around. I believe the fix introduced back then in brianc/node-packet-reader#3 should solve the problem here.