Question, out of curiosity: Is there a difference when you delete all lines
above and below the table, with and without adding a headline above?
One of my tables fluctuates around 150 rows and around 20 to 40
columns, overall a few hundred characters wide (columns with some
history window for each row). Almost all fields are just text although
I think this doesn't matter at all. The table starts at about line 50
and is followed by about 7600 lines. Since years I manipulate it at
least every few days without any slowness, often on much weaker
hardware than yours.
Maybe you can find a temporary workaround.