I think any further work on IDLE print speed should look at the entire path from print('x') to 'x' appearing in IDLE's Shell.  Where does the time go, what might be sped up?

I no longer think auto-squeezing should consider more than a single output string.

To continue this issue, I opened squeezer index issue #35855.  It describes what I think are the 2 main uses of auto-squeezing and several possible squeezer or related improvements, labeled for easy reference.

Some existing and new issues related to some of the off-topic messages:
#21261: Dict key tab completion.
#22121: Start in $HOME.
#24776: Configdialog font tab user interface -- add comment.
#25522: Save-as warning -- include unimportable names.
#28775: Set start-up directory
#32761: Modern Mac Keyset.
#33397: Change font size with cntl +- (text view first).

#35763: Calltips: make positional note smaller.
#35768: Detecting monospaced fonts with font sample -- automeasure.
#35769: ''Untitled" to "untitled" (fixed).