diff --git a/libraries/AP_Math/location.cpp b/libraries/AP_Math/location.cpp
index eebaa877f4..87f270b970 100644
--- a/libraries/AP_Math/location.cpp
+++ b/libraries/AP_Math/location.cpp
@@ -26,24 +26,8 @@
 
 float longitude_scale(const struct Location &loc)
 {
-#if HAL_CPU_CLASS < HAL_CPU_CLASS_150
-    static int32_t last_lat;
-    static float scale = 1.0;
-    // don't optimise on faster CPUs. It causes some minor errors on Replay
-    if (labs(last_lat - loc.lat) < 100000) {
-        // we are within 0.01 degrees (about 1km) of the
-        // same latitude. We can avoid the cos() and return
-        // the same scale factor.
-        return scale;
-    }
-    scale = cosf(loc.lat * 1.0e-7f * DEG_TO_RAD);
-    scale = constrain_float(scale, 0.01f, 1.0f);
-    last_lat = loc.lat;
-    return scale;
-#else
     float scale = cosf(loc.lat * 1.0e-7f * DEG_TO_RAD);
     return constrain_float(scale, 0.01f, 1.0f);
-#endif
 }