From fef41ad9add3cee3513ccd3efd86c1a1248e43b8 Mon Sep 17 00:00:00 2001
From: Lukas Devos <ldevos98@gmail.com>
Date: Wed, 26 Feb 2025 10:03:36 -0500
Subject: [PATCH] performance improvement

---
 src/operators/abstractmpo.jl | 21 +++++++++++++++++----
 1 file changed, 17 insertions(+), 4 deletions(-)

diff --git a/src/operators/abstractmpo.jl b/src/operators/abstractmpo.jl
index b0de56ce..938b26a5 100644
--- a/src/operators/abstractmpo.jl
+++ b/src/operators/abstractmpo.jl
@@ -196,10 +196,23 @@ end
 # TODO: diagram
 
 function _fuse_mpo_mpo(O1::MPOTensor, O2::MPOTensor, Fₗ, Fᵣ)
-    return @plansor O′[-1 -2; -3 -4] := Fₗ[-1; 1 2] *
-                                        O2[1 3; -3 5] *
-                                        O1[2 -2; 3 4] *
-                                        conj(Fᵣ[-4; 5 4])
+    return if O1 isa BraidingTensor && O2 isa BraidingTensor
+    elseif O1 isa BraidingTensor
+        @plansor O′[-1 -2; -3 -4] := Fₗ[-1; 1 2] *
+                                     O2[1 3; -3 5] *
+                                     τ[2 -2; 3 4] *
+                                     conj(Fᵣ[-4; 5 4])
+    elseif O2 isa BraidingTensor
+        @plansor O′[-1 -2; -3 -4] := Fₗ[-1; 1 2] *
+                                     τ[1 3; -3 5] *
+                                     O1[2 -2; 3 4] *
+                                     conj(Fᵣ[-4; 5 4])
+    else
+        @plansor O′[-1 -2; -3 -4] := Fₗ[-1; 1 2] *
+                                     O2[1 3; -3 5] *
+                                     O1[2 -2; 3 4] *
+                                     conj(Fᵣ[-4; 5 4])
+    end
 end
 
 """