diff --git a/Makefile b/Makefile
index 012a03b231..5e9cbb6303 100644
--- a/Makefile
+++ b/Makefile
@@ -933,7 +933,7 @@ LTO_FLAGS           := $(OPTIMISATION_BASE) $(OPTIMISE_DEFAULT)
 
 else ifeq ($(TARGET),$(filter $(TARGET),$(F3_TARGETS)))
 OPTIMISE_DEFAULT    := -O2
-OPTIMISE_SPEED      := -O3
+OPTIMISE_SPEED      := -Ofast
 OPTIMISE_SIZE       := -Os
 
 LTO_FLAGS           := $(OPTIMISATION_BASE) $(OPTIMISE_SPEED)