program works with maxima 5.29.1 but freezes with maxima 5.30.0

It seems that expand, not subst causes the problem. Does maxima show you 
the expr1 in the end of the attached program? I cannot see it, maxima 
consums all available memory and just hangs up.
> Dmitry Shkirmanov<piminusmeson at bk.ru>  writes:
>    
>> Hello, list. I have wxmaxima program that takes a few seconds to run
>> with maxima 5.29.1. But  in maxima 5.30.0 it freezes.  Is there any
>> way to make it work with maxima 5.30?
>>
>> The program is attached. Sorry, i cannot provide more simple example
>> as i have no idea what is going on.
>>      
> Well, I had a quick play and I'm pleased to say that the program doesn't
> hang in the scarily huge substitution (although it took about 3 minutes
> on my laptop). However, the next (and last) line of your code is a call
> to ratsimp. It ran for more than five minutes before I killed it.
>
> The result of the massive substitution was rather enormous, though. I
> guess it wasn't on the previous version? I can't really guess what it
> should have been because I don't understand the maths behind what you're
> doing.
>
> My *guess* is that something simplified massively when you did the big
> substitution on the previous version of Maxima and, as a result, the
> runtime was reasonable. Probably, something is getting simplified
> slightly differently with 5.30.0 and either one of your subscripted
> values (e.g. SK3_VEK_uu_VEK_uu[b,c,b,c]) or the matching part of
> any_expr has a slightly different form. Since subst() matches
> syntactically, this means the substitution doesn't happen and you end up
> with this massive unwieldy expression instead of something you can work
> with.
>
> Maybe you could try doing the substitution a bit at a time to see what's
> going wrong? I've used things like
>
> slow_subst (lst, expr) :=
>    (for x in lst do
>       (print ("Doing: ", x), expr: ratsimp (subst (x, expr))),
>     expr)$
>
> in the past to see how things are going. You could also print out the
> successive values of expr: maybe that would show you where the
> substitution was misbehaving.
>
> Rupert
>    
>
>
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