Using eager loading in GenerateTournamentMatches and AdvanceWrestler, generating/manipulating in-memory, and doing a single bulk insert or update at the end.

app/services/tournament_services/pool_generation.rb

@@ -1,35 +1,46 @@
 class PoolGeneration
-	def initialize(weight)
+	def initialize(weight, wrestlers: nil)
 		@weight = weight
 		@tournament = @weight.tournament
 		@pool = 1
+    @wrestlers = wrestlers
 	end
 
 	def generatePools
-		GeneratePoolNumbers.new(@weight).savePoolNumbers
+		GeneratePoolNumbers.new(@weight).savePoolNumbers(wrestlers: wrestlers_for_weight, persist: false)
+		rows = []
 		pools = @weight.pools
 		while @pool <= pools
-			roundRobin
+			rows.concat(roundRobin)
 			@pool += 1
 		end
+    rows
 	end		
 
 	def roundRobin
-		wrestlers = @weight.wrestlers_in_pool(@pool)
+		rows = []
+		wrestlers = wrestlers_for_weight.select { |w| w.pool == @pool }
 		pool_matches = RoundRobinTournament.schedule(wrestlers).reverse
 		pool_matches.each_with_index do |b, index|
 			round = index + 1
 			bouts = b.map
 			bouts.each do |bout|
 				if bout[0] != nil and bout[1] != nil
-					@tournament.matches.create(
+					rows << {
 						w1: bout[0].id,
 						w2: bout[1].id,
+						tournament_id: @tournament.id,
 						weight_id: @weight.id,
 						bracket_position: "Pool",
-						round: round)
+						round: round
+					}
 				end
 			end
 		end
+		rows
 	end
+
+  def wrestlers_for_weight
+    @wrestlers || @weight.wrestlers.to_a
+  end
 end