What about "InterSystems ObjectScript" ?
>>> short ISOS ??  😉

Fully agree with your suggestion of an Abstract Class.
It's in fact the modern equivalent of the old .INC approach

much more simple with 2 identic .INT routines a1 and a2​​

ROUTINE a1 [Type=INC]  
load ;
  read !,"loops=",loop,! 
  do t1 hang 0.5 do t2 quit
next 
  set t1=$zh quit 
t1 
  set t0=$zh
  for i=1:1:loop do next
  write t1-t0,!
  quit 
t2 
  set t0=$zh
  for i=1:1:loop do next^a2
  write t1-t0,!
  quit

SAMPLES>d ^a1
loops=1000000
.081626
.136785
SAMPLES>

I just mean you can't do less:
the difference is even worse 40.3%

My approach was rather simple.

• in runtime any class has its .INT wich has its .OBJ
• the OBJ is in the partition.
  • if I stay inside the .OBJ  it's fine
  • if I have to load another .OBJ and then reload the original .OBJ it consumes processor cycles
  • both .OBJ can be assumed to be cached, so it's a pure memory exercise
• the difference of both variants is sub microscopic
  • so looping for 100 M is kind of zoom-in to get something visible
  • The 100 M are common to both scenarios and
  • the Global has only (800 Mb) >>> 8 bytes / record counted by 
• I decided for SQL Shell for its nice runtime display.

SUMMARY: There is a difference.
But I wouldn't bend a little finger to attack it. (not even on PDP-11)
This is nothing where performance comes from.  

OK - in UDL

IRIS for Windows (x86-64) 2024.3 (Build 217U) Thu Nov 14 2024 17:59:58 EST

ROUTINE anna [Type=INC] 
anna(name) 
 quit ""

A.HUGE.cls

Include anna 
Class A.HUGE Extends (%Persistent, %Populate)
{ 
 Property calc As %Integer [ Calculated, SqlComputeCode = { set {*}={%%ID}},    SqlComputed ]; 

ClassMethod fill(size) As %String [ SqlProc ]
{
 for i=1:1:size set ^A.HUGED(i)=""
 set ^A.HUGED=i
 quit $ZR_"="_@$ZR
} 

ClassMethod test1(val) As %String [ SqlProc ]
{
 quit ##class(A.PERSON).Anna(val)
} 
ClassMethod test2(val) As %String [ SqlProc ]
{
 quit $$anna(val)
} 
Storage Default
{
 <Data name="HUGEDefaultData">
 <Value name="1">
 <Value>%%CLASSNAME</Value>
 </Value>
 </Data>
 <DataLocation>^A.HUGED</DataLocation>
 <DefaultData>HUGEDefaultData</DefaultData>
 <IdLocation>^A.HUGED</IdLocation>
 <IndexLocation>^A.HUGEI</IndexLocation>
 <StreamLocation>^A.HUGES</StreamLocation>
 <Type>%Storage.Persistent</Type>
} 
}

A.PERSON.cls

Include anna 
Class A.PERSON Extends %Persistent
{ 
 Property calc As %Integer [ Calculated, SqlComputeCode = { set {*}={%%ID}},  SqlComputed ];

ClassMethod fill(size) As %String [ SqlProc ]
{
 for i=1:1:size set ^A.PERSOND(i)=""
 set ^A.PERSOND=i
 quit $ZR_"="_@$ZR
} 

ClassMethod test1(val) As %String [ SqlProc ]
{
 quit ##class(A.PERSON).Anna(val)
} 

ClassMethod Anna(name As %String) As %String
{
 quit $$anna(name)
} 

Storage Default
{
 <Data name="PERSONDefaultData">
 <Value name="1">
 <Value>%%CLASSNAME</Value>
 </Value>
 </Data>
 <DataLocation>^A.PERSOND</DataLocation>
 <DefaultData>PERSONDefaultData</DefaultData>
 <IdLocation>^A.PERSOND</IdLocation>
 <IndexLocation>^A.PERSONI</IndexLocation>
 <StreamLocation>^A.PERSONS</StreamLocation>
 <Type>%Storage.Persistent</Type>
} }

The generated .INT proves it

Exactly.!
..#PARAMETER inserts a STRING
But >>>   $NAME() looks for a variable  also by indirection
 

USER>w $name("^rcc(1)")
 
W $NAME("^rcc(1)")
^
<SYNTAX>

USER>w $name(^rcc(1))
^rcc(1)
USER>s x="^rcc(1)"
USER>w $name(x)
x
USER>w $name(@x)
^rcc(1)
USER>

OOOOOPS 😮

confirm. It works and is independent of IRIS version 

That's a typical case,
where I write my personal ZZanyname  function  into %ZLANGF00.mac
to hide the details

which version ?

I tried and failed.
CLASS DOES NOT EXIST>%FromOref+8^%Library.DynamicObject.1 *%Library.EntityProjectionUtil
SAMPLES>w $zv
IRIS for Windows (x86-64) 2024.3 (Build 217U) Thu Nov 14 2024 17:59:58 EST

Just to confirm naming in COS 
GlobalName is everything between Caret ^ and left Parenthesis (
GlobalSubscript is everything within left and right Parenthesis  ( ) 

OK

To Stream needs 1 line 2 statements
 

ClassMethod personsidGET(messageRequest As dc.Sample.v3rest.requests.personsidGET) As %Stream.Object
{
 set stream=##class(%Stream.TmpCharacter).%New(),sc=##class(dc.Sample.Person).%OpenId(messageRequest.pathid).%JSONExportToStream(.stream)
 return stream
 }

To String is shorter (just 1 statement) as you don't need to initialize %String)

ClassMethod personsidGET(messageRequest As dc.Sample.v3rest.requests.personsidGET) As %String
 do ##class(dc.Sample.Person).%OpenId(messageRequest.pathid).%JSONExportToString(.string)
 return string
{