perf (Subalgebra.Basic): de-prioritize Subalgebra.module' (#9655)

This can send TC search off on a wild goose chase. Discussion on [Zulip](https://leanprover.zulipchat.com/#narrow/stream/287929-mathlib4/topic/Timeout.20in.20Submodule.20.28.F0.9D.93.9E.20K.29.20.28.F0.9D.93.9E.20K.29)
leanprover-community · Jan 11, 2024 · bb3b00a · bb3b00a
1 parent d191734
commit bb3b00a
Showing 1 changed file with 2 additions and 1 deletion.
diff --git a/Mathlib/Algebra/Algebra/Subalgebra/Basic.lean b/Mathlib/Algebra/Algebra/Subalgebra/Basic.lean
@@ -360,7 +360,8 @@ section
 /-! `Subalgebra`s inherit structure from their `Submodule` coercions. -/
 
 
-instance module' [Semiring R'] [SMul R' R] [Module R' A] [IsScalarTower R' R A] : Module R' S :=
+instance (priority := low) module' [Semiring R'] [SMul R' R] [Module R' A] [IsScalarTower R' R A] :
+    Module R' S :=
   S.toSubmodule.module'
 #align subalgebra.module' Subalgebra.module'