From a certain size, the whiteboard becomes too slow to handle.

[piiskop]

If the whiteboard is large enough it becomes very slow to handle. For instance, my chemistry exercises whiteboard is very slow already.

[lovasoa]

You should probably avoid posting your whiteboard URL publicly, since anyone could come and vandalize it.

It is a known issue that wbo becomes slow with huge boards.

What I can recommend is to split your large board into multiple smaller ones.