diff --git a/doc/src/sgml/regress.sgml b/doc/src/sgml/regress.sgml
index 4988908b540..ec50efa20a3 100644
--- a/doc/src/sgml/regress.sgml
+++ b/doc/src/sgml/regress.sgml
@@ -251,11 +251,11 @@ make check-world -j8 >/dev/null
 
   <para>
    Some test suites are not run by default, either because they are not secure
-   to run on a multiuser system or because they require special software.  You
-   can decide which test suites to run additionally by setting the
-   <command>make</command> or environment variable
-   <varname>PG_TEST_EXTRA</varname> to a whitespace-separated list, for
-   example:
+   to run on a multiuser system, because they require special software or
+   because they are resource intensive.  You can decide which test suites to
+   run additionally by setting the <command>make</command> or environment
+   variable <varname>PG_TEST_EXTRA</varname> to a whitespace-separated list,
+   for example:
 <programlisting>
 make check-world PG_TEST_EXTRA='kerberos ldap ssl'
 </programlisting>