stream/buffer: Reduces map lookups by using key struct (#1309)

* stream/buffer: Adds key map optimisation (cherry-pick)

* stream/buffer: Add buffer to DataHandler intermediary. Add field InitialUpdate bool to toggle when first update is seen for initial sync.

* whoops

* buffer: Add difference benchmarks for reference

* glorious: nits (reverting out of context changes)

* RM unused error that will be used later

* purge: benchmark

---------

Co-authored-by: Ryan O'Hara-Reid <ryan.oharareid@thrasher.io>

exchanges/stream/websocket.go

@@ -15,7 +15,7 @@ import (
 )
 
 const (
-	defaultJobBuffer = 1000
+	defaultJobBuffer = 5000
 	// defaultTrafficPeriod defines a period of pause for the traffic monitor,
 	// as there are periods with large incoming traffic alerts which requires a
 	// timer reset, this limits work on this routine to a more effective rate
@@ -62,7 +62,7 @@ func SetupGlobalReporter(r Reporter) {
 func New() *Websocket {
 	return &Websocket{
 		Init:              true,
-		DataHandler:       make(chan interface{}),
+		DataHandler:       make(chan interface{}, defaultJobBuffer),
 		ToRoutine:         make(chan interface{}, defaultJobBuffer),
 		TrafficAlert:      make(chan struct{}),
 		ReadMessageErrors: make(chan error),