Skip flush/read calls if no writes are made

Signed-off-by: Graham <gpe@openrs2.org>

archive/src/main/kotlin/org/openrs2/archive/cache/Js5ChannelHandler.kt

@@ -57,15 +57,21 @@ public class Js5ChannelHandler(
     }
 
     override fun channelReadComplete(ctx: ChannelHandlerContext) {
+        var flush = false
+
         while (inFlightRequests.size < maxInFlightRequests) {
             val request = pendingRequests.removeFirstOrNull() ?: break
             inFlightRequests += request
             ctx.write(request, ctx.voidPromise())
+
+            flush = true
         }
 
+        if (flush) {
             ctx.flush()
             ctx.read()
         }
+    }
 
     override fun exceptionCaught(ctx: ChannelHandlerContext, cause: Throwable) {
         releaseGroups()