Finally, I tried disabling the xshow,etc. implementations in Art and just
letting the GSGState handle them. Performance actually did not suffer
too much (despite another function call layer for every glyph), but
this resulted in some type of glyph mis-translation, displaying
scrambled characters. If I subtracted 28 from the value of each
UTF-8 character I passed in, the problem was fixed for ASCII,
however for other characters this caused a crash. If this issue
could be fixed, we might not need the Art implementation, though I
still think it makes sense to have it there..