I was never a Smalltalk programmer ((although I did once debug a fairly simple Smalltalk module by looking at the printout of the code). But I did work for awhile in an OOPL built on top of Smalltalk. That project died because it was too slow, but also because the Smalltalk vendor the project used went out of business, leaving an incompatible and expensive Smalltalk as the only one left standing. (At least that's what I was told.)

Today the project is written in C++, which had the advantages of being free and fast (and as far as I can tell, incomprehensible and prone to crashing).