Setting and changing data of signs creates unnecessary "extra" tags and causes slow downs

The bug

After playing around with some toggle-text signs I found the game would drop from 300+ fps down to around 10 after a few toggles, which seemed very odd. Looking away from the sign would return the fps back up high. Believe it has something to do with extra extra: [] tags appearing.

Running data merge block <pos> on a sign will add an extra: [] to each Text part of a sign. This effect also seems to stack. See images below. First is the initial sign data. Then I add an empty text, then I have done it 3 more times.