Inserting new lines in tables is slow on large tables (>100 rows)

I have a page containing two tables with 6 columns and about 150 lines each ... which in a production environment and our field of work is not even "really large". One of the columns holds the status macro (green,yellow, red) for every line within these tables.

It takes 9 seconds for Confluence to insert one new table line using either the toolbar or the shortcut.
Deleting the very same lines only takes the fraction of a second, though. Also, on small tables inserting a new record is quick as well. So it's seemingly the table length and number of tables on the page that slows it down.

Joe Wai Tye [Atlassian] tested this and found that it took him 2s on a page with one 150 row almost empty table, so with two tables we would be talking about the same order of mangnitude.

He also tested on Chrome and found it to be significantly faster in this respect.

So this looks like a browser specific performance issue.