Document IsNoImmediateMethodsObject

and add a hint to the documentation of vector and matrix objects
that setting this filter is recommended for them.
(There is no dedicated "performance hints" section for vector and
matrix objects yet.)

doc/ref/methsel.xml

@@ -323,6 +323,7 @@ For attributes and properties,
 one can install also <E>immediate methods</E>.
 
 <#Include Label="InstallImmediateMethod">
+<#Include Label="IsNoImmediateMethodsObject">
 
 </Section>
 

lib/matobj2.gd

@@ -141,6 +141,12 @@
 ##  However, row list matrices behave nearly like lists of row vectors
 ##  that insist on being dense and containing only vectors of the same
 ##  length and with the same base domain.
+##  <P/>
+##  Vector and matrix objects are not likely to benefit from &GAP;'s
+##  immediate methods (see section <Ref Sect="Immediate Methods"/>).
+##  Therefore it may be useful to set the filter
+##  <Ref Filt="IsNoImmediateMethodsObject"/> in the definition of new kinds
+##  of vector and matrix objects.
 ##  <#/GAPDoc>
 ##
 

lib/oper.g

@@ -210,16 +210,23 @@ fi;
 ##
 #F  IsNoImmediateMethodsObject(<obj>)
 ##
+##  <#GAPDoc Label="IsNoImmediateMethodsObject">
 ##  <ManSection>
-##  <Func Name="IsNoImmediateMethodsObject" Arg='obj'/>
+##  <Filt Name="IsNoImmediateMethodsObject" Arg='obj'/>
 ##
 ##  <Description>
-##  If this filter is set immediate methods will be ignored for <A>obj</A>. This
-##  can be crucial for performance for objects like PCGS, of which many are
-##  created, which are collections, but for which all those immediate
-##  methods for <C>IsTrivial</C> et cetera do not really make sense.
+##  If this filter is set immediate methods will be ignored for <A>obj</A>.
+##  This can be crucial for performance for objects like pcgs
+##  (see Section <Ref Sect="Polycyclic Generating Systems"/>), of which many
+##  are created, which are collections, but for which all those immediate
+##  methods for <Ref Prop="IsTrivial"/> et cetera do not really make sense.
+##  Other examples of objects in <Ref Filt="IsNoImmediateMethodsObject"/> are
+##  compressed vectors and matrices over small finite fields,
+##  see the sections <Ref Subsect="Row Vectors over Finite Fields"/> and
+##  <Ref Subsect="Matrices over Finite Fields"/>.
 ##  </Description>
 ##  </ManSection>
+##  <#/GAPDoc>
 ##
 BIND_GLOBAL("IsNoImmediateMethodsObject",
   NewFilter("IsNoImmediateMethodsObject"));