As you can see on the video, the following problems are with the 2017 wikitext editor if I edit big page:
- The loading of the page, preview mode and scrolling is extremely slow
- Selecting everything (Ctrl+A) causes shifting text, similar to T180678
- Cutting everything (Ctrl+X) is slow too
- Pasting the previous content is slow again and causes blank page and red underlines (similar to T176073). Solution: write a character and delete it
Size of the test page is ~68.000 bytes. By the way; editing "Weimari köztársaság" (~223.000 bytes) was a real pain.