diff --git a/src/cmp/cmpc-inliner.lsp b/src/cmp/cmpc-inliner.lsp
index d2a9be114..ed2457cbd 100644
--- a/src/cmp/cmpc-inliner.lsp
+++ b/src/cmp/cmpc-inliner.lsp
@@ -102,6 +102,11 @@
       (let ((other (inline-type-matches x types return-type)))
         (when other
           (setf output (choose-inline-info output other return-type return-rep-type)))))
+    (when (and (null output)
+               (get-sysprop fname 'should-be-inlined)
+               (>= (cmp-env-optimization 'speed) 1))
+      (cmpwarn-style "Could not inline call to ~S ~S - performance may be degraded."
+                     fname types))
     output))
 
 (defun to-fixnum-float-type (type)
diff --git a/src/cmp/cmpffi.lsp b/src/cmp/cmpffi.lsp
index aeaca653a..3c27f8a0a 100644
--- a/src/cmp/cmpffi.lsp
+++ b/src/cmp/cmpffi.lsp
@@ -326,6 +326,12 @@
 	   (otherwise
 	    (coercion-error))))
 	((:object)
+         #+sse2
+	 (case loc-rep-type
+	   ((:int-sse-pack :float-sse-pack :double-sse-pack)
+            (when (>= (cmp-env-optimization 'speed) 1)
+              (cmpwarn-style "Boxing a value of type ~S - performance degraded."
+                             loc-rep-type))))
 	 (wt-to-object-conversion loc-rep-type loc))
 	((:pointer-void)
 	 (case loc-rep-type
diff --git a/src/cmp/sysfun.lsp b/src/cmp/sysfun.lsp
index 82c3f56b2..f68729ee9 100644
--- a/src/cmp/sysfun.lsp
+++ b/src/cmp/sysfun.lsp
@@ -23,7 +23,7 @@
 (in-package "COMPILER")
 
 (defun def-inline (name safety arg-types return-rep-type expansion
-                   &key (one-liner t) (exact-return-type nil)
+                   &key (one-liner t) (exact-return-type nil) (inline-or-warn nil)
                    &aux arg-rep-types)
   (setf safety
 	(case safety
@@ -36,6 +36,8 @@
 		arg-types))
   (when (eq return-rep-type t)
     (setf return-rep-type :object))
+  (when inline-or-warn
+    (put-sysprop name 'should-be-inlined t))
   (let* ((return-type (if (and (consp return-rep-type)
                                (eq (first return-rep-type) 'values))
                           t