Thanks for all the replies. Byte count looks good enough for me, there is already a dedicated plugin to more refined statistics like count chars and words, for statusbar I believe byte count is enough.
However, the other editor I’m talking about (CudaText) doesn’t use Scintilla, it has its own editing component (ATSynEdit) that doesn’t use simple buffer storage to retrieve byte count, it has “list of lines” according to the dev so the count would be slow.
An optimization is possible by caching the size of each line, adding them up and then updating with edit events (typing one char sums 1…). But at the moment he don’t plan to work on it because it’s not that trivial as the editor supports multiple carets, multiple selections ans so on.
Just adding, other text editor I have installed here, Kate, displays not only chars count (precisely, not bytes) but also count of words in statusbar. However these counts aren’t instant, I can see they wait for like half a second without change in the text to update. Clearly it’s done this way because it’s not that cheap to be done instantly.