diff --git a/src/main.rs b/src/main.rs
index 98daddf1..fd22b304 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -193,26 +193,30 @@ fn main() {
             gl::Clear(gl::COLOR_BUFFER_BIT);
         }
 
-        {
-            let _sampler = meter.sampler();
+        if terminal.dirty() {
+            {
+                let _sampler = meter.sampler();
 
+                renderer.with_api(&props, |mut api| {
+                    // Draw the grid
+                    api.render_grid(terminal.grid(), &mut glyph_cache);
+
+                    // Also draw the cursor
+                    api.render_cursor(terminal.cursor(), &mut glyph_cache);
+                })
+            }
+
+            // Draw render timer
+            let timing = format!("{:.3} usec", meter.average());
+            let color = Rgb { r: 0xd5, g: 0x4e, b: 0x53 };
             renderer.with_api(&props, |mut api| {
-                // Draw the grid
-                api.render_grid(terminal.grid(), &mut glyph_cache);
+                api.render_string(&timing[..], &mut glyph_cache, &color);
+            });
 
-                // Also draw the cursor
-                api.render_cursor(terminal.cursor(), &mut glyph_cache);
-            })
+            terminal.clear_dirty();
+
+            window.swap_buffers().unwrap();
         }
-
-        // Draw render timer
-        let timing = format!("{:.3} usec", meter.average());
-        let color = Rgb { r: 0xd5, g: 0x4e, b: 0x53 };
-        renderer.with_api(&props, |mut api| {
-            api.render_string(&timing[..], &mut glyph_cache, &color);
-        });
-
-        window.swap_buffers().unwrap();
     }
 
     // TODO handle child cleanup
diff --git a/src/term.rs b/src/term.rs
index c254f6b9..1845d9e3 100644
--- a/src/term.rs
+++ b/src/term.rs
@@ -93,6 +93,9 @@ pub struct Term {
 
     /// Cell attributes
     attr: grid::CellFlags,
+
+    /// Whether state has changed and needs to be updated.
+    dirty: bool,
 }
 
 impl Term {
@@ -115,9 +118,18 @@ impl Term {
             tty: tty,
             tabs: tabs,
             attr: CellFlags::empty(),
+            dirty: false,
         }
     }
 
+    pub fn dirty(&self) -> bool {
+        self.dirty
+    }
+
+    pub fn clear_dirty(&mut self) {
+        self.dirty = false;
+    }
+
     pub fn grid(&self) -> &Grid {
         &self.grid
     }
@@ -153,6 +165,7 @@ impl Term {
 
     /// Set character in current cursor position
     fn set_char(&mut self, c: char) {
+        self.dirty = true;
         if self.cursor.x == self.grid.num_cols() as u16 {
             self.cursor.y += 1;
             self.cursor.x = 0;
@@ -187,14 +200,17 @@ impl ansi::Handler for Term {
 
     fn goto(&mut self, x: i64, y: i64) {
         println!("goto: x={}, y={}", x, y);
+        self.dirty = true;
         self.cursor.goto(x as u16, y as u16);
     }
     fn goto_row(&mut self, y: i64) {
+        self.dirty = true;
         println!("goto_row: {}", y);
         let x = self.cursor_x();
         self.cursor.goto(x, y as u16);
     }
     fn goto_col(&mut self, x: i64) {
+        self.dirty = true;
         println!("goto_col: {}", x);
         let y = self.cursor_y();
         self.cursor.goto(x as u16, y);
@@ -203,21 +219,25 @@ impl ansi::Handler for Term {
     fn insert_blank(&mut self, num: i64) { println!("insert_blank: {}", num); }
 
     fn move_up(&mut self, rows: i64) {
+        self.dirty = true;
         println!("move_up: {}", rows);
         self.cursor.advance(-rows, 0);
     }
 
     fn move_down(&mut self, rows: i64) {
+        self.dirty = true;
         println!("move_down: {}", rows);
         self.cursor.advance(rows, 0);
     }
 
     fn move_forward(&mut self, cols: i64) {
+        self.dirty = true;
         println!("move_forward: {}", cols);
         self.cursor.advance(0, cols);
     }
 
     fn move_backward(&mut self, spaces: i64) {
+        self.dirty = true;
         println!("move_backward: {}", spaces);
         self.cursor.advance(0, -spaces);
     }
@@ -226,6 +246,7 @@ impl ansi::Handler for Term {
     fn move_down_and_cr(&mut self, rows: i64) { println!("move_down_and_cr: {}", rows); }
     fn move_up_and_cr(&mut self, rows: i64) { println!("move_up_and_cr: {}", rows); }
     fn put_tab(&mut self, mut count: i64) {
+        self.dirty = true;
         println!("put_tab: {}", count);
 
         let mut x = self.cursor_x();
@@ -245,6 +266,8 @@ impl ansi::Handler for Term {
     /// Backspace `count` characters
     #[inline]
     fn backspace(&mut self, count: i64) {
+        println!("backspace");
+        self.dirty = true;
         self.cursor.x -= 1;
         self.set_char(' ');
     }
@@ -252,12 +275,15 @@ impl ansi::Handler for Term {
     /// Carriage return
     #[inline]
     fn carriage_return(&mut self) {
+        println!("carriage_return");
+        self.dirty = true;
         self.cursor.x = 0;
     }
 
     /// Linefeed
     #[inline]
     fn linefeed(&mut self) {
+        self.dirty = true;
         println!("linefeed");
         // TODO handle scroll? not clear what parts of this the pty handle
         if self.cursor_y() + 1 == self.grid.num_rows() as u16 {
@@ -284,6 +310,7 @@ impl ansi::Handler for Term {
     fn save_cursor_position(&mut self) { println!("save_cursor_position"); }
     fn restore_cursor_position(&mut self) { println!("restore_cursor_position"); }
     fn clear_line(&mut self, mode: ansi::LineClearMode) {
+        self.dirty = true;
         println!("clear_line: {:?}", mode);
         match mode {
             ansi::LineClearMode::Right => {
@@ -298,6 +325,7 @@ impl ansi::Handler for Term {
         }
     }
     fn clear_screen(&mut self, mode: ansi::ClearMode) {
+        self.dirty = true;
         println!("clear_screen: {:?}", mode);
         match mode {
             ansi::ClearMode::Below => {
@@ -321,6 +349,7 @@ impl ansi::Handler for Term {
     fn clear_tabs(&mut self, mode: ansi::TabulationClearMode) { println!("clear_tabs: {:?}", mode); }
     fn reset_state(&mut self) { println!("reset_state"); }
     fn reverse_index(&mut self) {
+        self.dirty = true;
         println!("reverse_index");
         // if cursor is at the top
         if self.cursor.y == 0 {