The first one is I reported problems with scrolling when TeX-fold-mode is on. I am unsure why, but the issue is solved by removing BIDI text
(setq-default bidi-display-reordering nil)
If I do not do this, and use TeX-fold-mode in a big buffer, scrolling up and down with C-n, C-p or arrows, becomes unbearably slow on my computer. I am using visual-line-mode and proportional fonts, but that shouldn't be the culprit, as once I disable BIDI everything goes very nice.
The second one relates to fonts with TeX-fold-mode and subscripts.As you see below, the \psi macro is properly folded to a Unicode character, but the size and position are wrong.
In contrast, the unfolded text reads just fine
and the $\psi$ character in any other position is properly displayed.
I have not been able to find out what part of font faces, tex-fold or font-latex may be interfering with this.