diff --git a/doc/low-memory.rst b/doc/low-memory.rst
index d2c47f41..241b23b8 100644
--- a/doc/low-memory.rst
+++ b/doc/low-memory.rst
@@ -2,6 +2,26 @@
 Low memory environments
 =======================
 
+One important portability target are low memory environments.  The default
+Duktape options are quite memory conservative, and significant Ecmascript
+programs can be executed with, say, 1 megabyte of memory.  Currently realistic
+memory targets are roughly:
+
+* 256kB flash memory (code) and 256kB system RAM
+
+  - Duktape compiled with default options is feasible
+
+* 256kB flash memory (code) and 128kB system RAM
+
+  - Duktape feature options are needed to reduce memory usage
+
+  - A custom memory allocation with manually tuned pools may be required
+
+  - Only very small programs can currently be executed
+
+This document describes suggested feature options for reducing Duktape
+memory usage for memory-constrained environments.
+
 Suggested feature options
 =========================
 
diff --git a/doc/timing-sensitive.rst b/doc/timing-sensitive.rst
index e9e371c7..ab82bae5 100644
--- a/doc/timing-sensitive.rst
+++ b/doc/timing-sensitive.rst
@@ -2,6 +2,13 @@
 Timing sensitive environments
 =============================
 
+Timing sensitive environments include e.g. games.  In these environments
+long blocking times are problematic.  Stop-and-go garbage collection is
+also a potential issue.
+
+This document describes suggested feature options for reducing Duktape
+latency in timing sensitive environments.
+
 Suggested feature options
 =========================