-#!+(or cgc gencgc) (progn
-#!-sb-fluid (declaim (inline dynamic-usage))
-(def-c-var-frob dynamic-usage "bytes_allocated"))
-
+#!-gencgc
+(progn
+ ;; This is called once per PROFILEd function call, so it's worth a
+ ;; little possible space cost to reduce its time cost.
+ #!-sb-fluid
+ (declaim (inline current-dynamic-space-start))
+ (def-c-var-frob current-dynamic-space-start "current_dynamic_space"))
+
+#!-sb-fluid
+(declaim (inline dynamic-usage)) ; to reduce PROFILEd call overhead
+#!+(or cgc gencgc)
+(def-c-var-frob dynamic-usage "bytes_allocated")