Optimize rendering by using Ropey::byte_slice

This avoids costly conversions via byte_to_char (which are then
reversed back into bytes internally in Ropey).

Reduces time spent in slice/byte_to_char from ~24% to ~5%.

1 files changed, 1 insertions, 4 deletions

diff --git a/helix-core/src/graphemes.rs b/helix-core/src/graphemes.rs
index aa898684..c0c61775 100644
--- a/helix-core/src/graphemes.rs
+++ b/helix-core/src/graphemes.rs
@@ -333,10 +333,7 @@ impl<'a> Iterator for RopeGraphemes<'a> {
         }
 
         if a < self.cur_chunk_start {
-            let a_char = self.text.byte_to_char(a);
-            let b_char = self.text.byte_to_char(b);
-
-            Some(self.text.slice(a_char..b_char))
+            Some(self.text.byte_slice(a..b))
         } else {
             let a2 = a - self.cur_chunk_start;
             let b2 = b - self.cur_chunk_start;